Osmosis - GCSE Science Required Practical

00:12:13
https://www.youtube.com/watch?v=oieXYuQm_xE

Sintesi

TLDRThe video details a practical experiment on osmosis using potato cylinders submerged in solutions with varying sucrose concentrations. The initial steps involve preparing and cutting uniform potato samples to ensure reliable comparison of results. The experiment employs distilled water, 0.25, and 0.5 molar sucrose solutions. Measurements of both length and mass are meticulously recorded before and after immersion in the solutions over 24 hours. The video further explains calculating percentage changes in mass to identify trends of osmosis based on different solution concentrations. It highlights an increase in mass in distilled water due to water influx and a decrease in 0.5 molar sucrose solution, asserting the principle of osmosis. Recommendations for enhanced accuracy, such as using vernier calipers, and addressing the effect of solution evaporation with a bun cover, are also discussed.

Punti di forza

  • 🔬 The experiment demonstrates osmosis using potato plant tissue and different solution concentrations.
  • 🥔 Potato cylinders are used to maintain consistent samples for reliable results.
  • 📏 Measurements of length and mass are crucial and taken before and after soaking in solutions.
  • 💧 In distilled water, potato cylinders gain mass due to water influx by osmosis.
  • 🔍 Vernier calipers could improve measurement accuracy over basic rulers.
  • 📉 A decrease in mass is observed in higher sucrose concentration solutions, indicating water loss.
  • 💡 Percentage change calculations help compare the effect of each solution on osmosis.
  • 🧪 Various sucrose solutions are used to interpret the relationship between concentration and osmosis.
  • 🚫 A bun is used to prevent evaporation during experimentation.
  • 📊 A line of best fit can indicate the internal sugar concentration of the potato by neutralizing mass changes.

Linea temporale

  • 00:00:00 - 00:05:00

    The video begins with an overview of an osmosis practical experiment focused on testing the effects of different solution concentrations on potato tissue. To ensure consistency and allow for easy comparison of results, the narrator uses a cork board to cut potato samples of the same diameter. These samples are then trimmed to remove the impermeable potato skin and cut to approximately 3 cm in length using a ruler, ensuring uniform sample size. Each sample is then measured for both length and mass using a ruler and a top pan balance respectively, with each cylinder weighing in at exactly 2.92 grams. Three different solutions are prepared, including distilled water, 0.25 molar sucrose, and 0.5 molar sucrose, poured into separate tubes labeled clearly to avoid mix-up. A bun is added to tubes to prevent evaporation. This meticulous preparation allows the samples to absorb or lose water under controlled conditions, making it easier to later analyze the impact of osmosis.

  • 00:05:00 - 00:12:13

    After 24 hours, the potatoes are removed from their solutions, dried to remove surface moisture without losing water from within the tissue, and then measured for changes in length and mass. The potato in distilled water increased two millimeters in length and gained mass, while the one in the 0.25 molar sugar saw a slight mass increase but no length change. Conversely, the potato in 0.5 molar sucrose lost mass and became floppier, hinting at a higher water loss. This empirical data is used to determine water migration in the potatoes, with results recorded meticulously for analysis. Differences in initial measurements necessitated calculating percentage change to standardize comparisons across samples. The narrative concludes with an interpretation of results: as sugar concentration in the solution increases, the osmotic activity increases, leading to greater water loss from potatoes. The plotted graph illustrates this trend and identifies the isotonic point where potato mass does not change, indicating the internal concentration of the potato tissue.

Mappa mentale

Mind Map

Domande frequenti

  • What is the purpose of the osmosis experiment?

    The purpose is to observe the effect of different concentrations of solutions on the osmosis process in plant tissue, specifically potatoes.

  • Why are all potato cylinders cut to the same length?

    Cutting all the potato cylinders to the same length ensures consistency and allows for easier comparison of results.

  • What are the concentrations of solutions used in the experiment?

    The concentrations used are distilled water, 0.25 molar sucrose, and 0.5 molar sucrose solutions.

  • What equipment is used to measure the potato cylinders?

    A basic ruler and a top pan balance accurate to two decimal places are used for measuring length and mass, respectively.

  • How are the experimental results recorded?

    Results are recorded by measuring the change in length and mass of potato cylinders before and after placing them in solutions.

  • How is the percentage change in mass calculated?

    The percentage change is calculated by taking the difference in mass (current mass minus initial mass), dividing by the initial mass, and multiplying by 100.

  • Why is a bun placed over the test tube?

    A bun is placed over the test tube to prevent evaporation of the solution, especially in hot weather.

  • What does a decrease in mass indicate in this experiment?

    A decrease in mass indicates osmosis where water has moved out of the potato cells due to a higher concentration of sugar in the solution.

  • Why is a line of best fit useful in the analysis?

    It's useful to determine the point where the sugar concentration inside and outside the potato tissue is the same, indicating no net osmosis.

  • What are possible improvements suggested for the experiment?

    Using vernier calipers for more accurate length measurements is suggested as an improvement.

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Sottotitoli
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Scorrimento automatico:
  • 00:00:00
    right today we're going to look at the
  • 00:00:01
    required practical for osmosis looking
  • 00:00:04
    at the effect of different
  • 00:00:07
    concentrations of solutions on some
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    plant tissue our plant tissue being a
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    potato and we'll talk more about the
  • 00:00:14
    different concentration of solutions in
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    a moment but what I want to do first is
  • 00:00:17
    prepare my potato my plant tissue to do
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    that we have a cork board this is going
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    to allow me to take samples and potato
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    that are all the same diameter and
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    that's going to important so I can
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    compare my results more easily so here
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    is one cylinder now I'm going to cut
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    three cylinders I'm just going to set up
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    three different concentrations of
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    solution today so one cylinder to
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    cinders and my third potato
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    cinder notice these are all coming from
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    the same potato that should help keep my
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    results more consistent each other
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    easier for me to compare my results with
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    each other now what I want to do now is
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    just going to cut the ends off the ends
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    of these as a potato skin it's going to
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    move those they are impermeable they
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    will not allow water into the tissue
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    that's not what we're looking for this
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    experiment all about water either moving
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    into the plant cells or out of the plant
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    cells and that's really what osmosis is
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    I've now got where cylinders they are
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    all the same length which is vital or
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    approximately the same length so again
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    helping me to compare my results later
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    on but the instructions asked me to
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    measure them into three centimeter
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    lengths so I'm just going to go with
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    that but they are about same length
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    which is fine so the cut each one now
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    I'm only using a ruler here not the most
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    accurate way of measuring these but
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    we'll get will go with it
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    I'll talk about that in a moment I've
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    got one
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    - so that's again three centimeters get
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    getting as close as I can to three
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    centimeters while using a ruler three so
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    I now have three as identical I can get
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    them pieces of potato tissue
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    well I now need to do is measure them
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    very accurately as best as I can I'm
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    going to measure both their lengths
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    using a ruler and also their maths using
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    the top pan balance so the ruler I can
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    measure them and that one is exactly
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    thirty millimeters so they are all
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    exactly 30 minutes millimeters now I
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    need to record those results I need to
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    note sure that I know the length of each
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    sender if they're different they're all
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    the same in this case it doesn't really
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    matter so need to recall those in my
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    results table and then it's away their
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    mass so on this balance what I'm using
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    here is a balance that has two decimal
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    places on it so it is accurate to a
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    hundredth of a gram so I'm using a very
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    high resolution top top and balance here
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    to get very accurate result we're going
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    to see probably very small changes in
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    our mass here which is why we need to
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    use this piece of equipment why it's
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    appropriate and we have a mass of 2.92
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    grams so I need to record that in my
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    results table having recorded the length
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    and mass this potato cylinder it now go
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    to my boiling tube boiling tube I need
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    to place some liquid into it now I'm
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    going to start with distilled water so
  • 00:03:28
    this is pure water so it's our first one
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    so the puts in here I'm going to get
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    down level I level of the measuring
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    cylinder so I can very measure very
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    accurately 10 millimeter milliliters of
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    distilled water so go try to keep
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    everything exactly the same between all
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    my expense to help me compare my results
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    there's my distilled water very
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    important and I'll label this so I know
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    what's in here
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    so I can't mix up my samples which would
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    be make it very hard to work out what's
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    happened this experiment it's so hot at
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    the moment I am going to add a bun to
  • 00:04:16
    this not necessary if we only do this
  • 00:04:19
    experiment for a short period of time or
  • 00:04:21
    if the weather is not too hot this will
  • 00:04:23
    help prevent any evaporation liquid out
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    of the tube so this is my first sample I
  • 00:04:28
    need to do that for my remaining two
  • 00:04:30
    cylinders adding 0.25 molar sucrose so
  • 00:04:36
    this is slightly sugary solution so it's
  • 00:04:39
    got some sugar added to the water so
  • 00:04:41
    this is sort of slightly sugary water
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    and I'm going to add to another one 0.5
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    molar sucrose this is a stronger
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    solution of sugar and we need to see how
  • 00:04:52
    these three solutions affect the potato
  • 00:04:55
    now I have set some up earlier I did
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    this yesterday allowing this to run for
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    24 hours to help my results hopefully
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    increase a bit so it should get bigger
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    results and if I just do it for a short
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    period time so Blue Peter moment income
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    some that I made earlier so I no need to
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    collect my results having left my
  • 00:05:13
    samples overnight and so we're going to
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    show you how to do that so get my
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    distilled water sample first which is
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    this one now I need to pour away the
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    water I'm going to collect the potato
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    cylinder into a sieve it's off camera
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    but I'm just going to pour it into a
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    sieve it's quite damp it's quite wet
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    wetter than when I first got it from
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    potato so we just remove the excess
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    water on the outside of this that might
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    affect the results quickest way to do
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    that it's very quickly roll it onto the
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    main paper towel it does not want to sit
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    on the green paper towel that could draw
  • 00:05:47
    liquid out of the tato which would
  • 00:05:50
    affect my results but I have now removed
  • 00:05:51
    the excess liquid so now measure my
  • 00:05:54
    length again I'm using a ruler as I did
  • 00:05:58
    before and has increased to 32
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    millimetres length it's an increase of
  • 00:06:03
    two millimeters there is another piece
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    of clip we could use to measure length
  • 00:06:08
    called vernier calipers these measure
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    length more accurately so we could use
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    these as an improvement to the expense
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    but we're not going to do that today
  • 00:06:15
    I now need to measure the mass of my
  • 00:06:18
    potato after it's being distilled water
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    for 24 hours on to the balance and it is
  • 00:06:25
    now three point 1/2 grams that is that's
  • 00:06:30
    actually increased from 2.9 for grams so
  • 00:06:33
    again we have an increase here in in our
  • 00:06:36
    results an increase in length and an
  • 00:06:37
    increase in mass with distilled water
  • 00:06:39
    these results must be written down in
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    your results table so I've gotta click
  • 00:06:43
    those results and I need to do the same
  • 00:06:45
    for the other two solutions so they're
  • 00:06:48
    0.25 molar sugar solution again so get
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    pour away the water
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    Claire toss cylinder quickly dry it
  • 00:07:01
    measure the length it should thirty
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    millimeters no real change there measure
  • 00:07:12
    the mass which is three point zero six
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    grams which is a very small increase
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    yesterday's result before putting into
  • 00:07:20
    the sugar solution was two point nine
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    six grams so a very very small increase
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    hit so having measured that one I need
  • 00:07:27
    to write the results down and move on to
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    my third sample which is the potato left
  • 00:07:31
    in the strongest solution of sugar
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    naught point five molar sugar solution
  • 00:07:36
    so again collect my potato cylinder
  • 00:07:40
    quickly dry on the paper removing excess
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    liquid now I can actually feel this one
  • 00:07:46
    it's quite floppy compared to the others
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    which gives us a clue as well how
  • 00:07:51
    results may look in a moment I measure
  • 00:07:54
    the length hasn't particular changed may
  • 00:07:56
    have gone down very slightly I can't
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    really tell the actress's ruler so the
  • 00:08:01
    length may decrease slightly I think
  • 00:08:02
    that was about thirty millimeters hasn't
  • 00:08:04
    really changed measure the mass and the
  • 00:08:08
    mass is now two point six two grams
  • 00:08:10
    there's a decrease yesterday I measured
  • 00:08:13
    this at two point eight seven grams so
  • 00:08:15
    it has decreased in mass so the other
  • 00:08:18
    two samples so an increase in mass this
  • 00:08:21
    one has decreased in mass so there's a
  • 00:08:22
    difference there need to be thinking
  • 00:08:24
    about why the two different results have
  • 00:08:26
    occurred
  • 00:08:27
    so we've now collect our results
  • 00:08:29
    the next stage is to think about what we
  • 00:08:34
    can do with that data so you need to
  • 00:08:36
    calculate the difference in mass and the
  • 00:08:38
    difference in length from yesterday to
  • 00:08:41
    today you some of them the mass would
  • 00:08:43
    have increased and for some of them the
  • 00:08:45
    mass will have decreasing you to work
  • 00:08:47
    that out okay so I've measured my length
  • 00:08:51
    of my cinders yesterday
  • 00:08:53
    and today I've made my mass my cinders
  • 00:08:54
    yesterday and today my potato tissue and
  • 00:08:57
    we've seen this in difference already we
  • 00:08:58
    need to calculate the exact differences
  • 00:09:00
    so what I'd like what you now need to do
  • 00:09:02
    is take your length today your final
  • 00:09:06
    length and minus the initial length to
  • 00:09:09
    get a difference has it increased or
  • 00:09:11
    decreased in length so you may get a
  • 00:09:12
    negative number just decrease in length
  • 00:09:14
    you may get a positive number is
  • 00:09:15
    increase in length so you do the same
  • 00:09:17
    for all three senators then do the same
  • 00:09:19
    for mass so again mass today your second
  • 00:09:25
    mass minus the initial mass and get
  • 00:09:28
    looking you may get a positive number an
  • 00:09:30
    increase in mass you might get a
  • 00:09:31
    negative number a decrease in maths
  • 00:09:35
    unfortunately because potations were not
  • 00:09:38
    actually all identical to start now I
  • 00:09:40
    did try very hard to keep them identical
  • 00:09:42
    but they were not all the same mass at
  • 00:09:44
    the start that makes it very hard to
  • 00:09:46
    compare my results what I need to do is
  • 00:09:49
    a little calculation that makes it much
  • 00:09:52
    easier to compare my results a
  • 00:09:53
    calculation called percentage change so
  • 00:09:57
    now you've got your change in results
  • 00:09:59
    you take that change in mass so your
  • 00:10:02
    mass today
  • 00:10:03
    minus your initial mass divide it by
  • 00:10:06
    your initial mass multiply that number
  • 00:10:09
    by a hundred and you have a percentage
  • 00:10:12
    change so again if it is increasing mass
  • 00:10:14
    to have a positive percentage increase
  • 00:10:17
    and if you have decreasing mass with a
  • 00:10:19
    negative percentage change and some
  • 00:10:22
    potato did increase in mass and some did
  • 00:10:23
    decrease in this nation okay you should
  • 00:10:26
    be thinking about why that has happened
  • 00:10:28
    if I did quite a few results more than
  • 00:10:31
    I've done today you might get a graph
  • 00:10:33
    that looks something like this
  • 00:10:35
    so here's a what I've just sketched
  • 00:10:37
    earlier it's not not particularly
  • 00:10:39
    accurate but does show you the pattern
  • 00:10:41
    you would
  • 00:10:41
    expect to see so you can see here over
  • 00:10:44
    here we've got a very pure water and our
  • 00:10:46
    potato should gain a mass and as our
  • 00:10:49
    concentration of sugar increases so as
  • 00:10:51
    we add more and more sugar dissolve more
  • 00:10:54
    more sugar in in the water
  • 00:10:56
    we increase the sugar concentration you
  • 00:11:00
    might talk about decreasing the
  • 00:11:02
    concentration of the water we might see
  • 00:11:05
    that the results decrease so initially
  • 00:11:07
    our gaining mass gets less and less and
  • 00:11:11
    less notice the language i've used there
  • 00:11:12
    the gain in mass is decreasing
  • 00:11:16
    we then get a point where our mass may
  • 00:11:20
    or may not change we might not see that
  • 00:11:22
    in our experiment but from a line of
  • 00:11:23
    best fit we can see there's a point
  • 00:11:25
    where there is no change in mass that's
  • 00:11:28
    a very useful bit of information this
  • 00:11:30
    tells you actually how much sugar is
  • 00:11:33
    within the potato tissue itself though
  • 00:11:35
    the the water concentration the sugar
  • 00:11:38
    concentration within the sugar or in the
  • 00:11:39
    potato is here so we can estimate that
  • 00:11:42
    by where this line of best fit crosses
  • 00:11:44
    this axis and then down here so down
  • 00:11:47
    below this axis we have a loss of mass
  • 00:11:50
    that is getting bigger and bigger so an
  • 00:11:53
    increasing loss of mass so the more
  • 00:11:56
    concentrated sugar the more water the
  • 00:11:59
    more mass the potato should lose so
  • 00:12:02
    that's down here so this is what's
  • 00:12:03
    happening down here and that is osmosis
Tag
  • osmosis
  • experiment
  • plant tissue
  • potato
  • sucrose concentration
  • measurement
  • mass change
  • percentage change
  • practical science
  • solution preparation