How To Find Percent Change In Mass
Transport in cells
Improvidence is the movement of particles from a high to lower concentration. Osmosis is the diffusion of water across a membrane. Active send moves particles from depression to higher concentration. Exam / not-exam assessments for students taking qualifications during the pandemic may be bailiwick to change. Delight bank check with your teacher.
Maths - Calculating pct gain and loss of mass in osmosis
Analysing results
The investigation cannot exist based on changes in mass from merely one potato cylinder. In scientific tests, we must ensure a number of examples are used to allow for anomalous results and variation.
Pct changes in mass must exist calculated for each cylinder and mean calculated.
A graph is plotted of modify in mass, in per cent, confronting concentration of sucrose . Concentrations of solutions are shown as percentages. A larger number means a higher concentration.
Where potato cylinders accept gained in mass, the change will be positive. Where potato cylinders have decreased in mass, the change will be negative.
| Concentration of sucrose % | Average alter in mass (%) |
|---|---|
| 0 | +26.8 |
| 20 | +5.0 |
| forty | −7.7 |
| threescore | −17.9 |
| eighty | −26.0 |
| 100 | −31.four |
Where the plotted line crosses the horizontal axis at 0 per cent change in mass, the sucrose concentration of the solution is equal to the concentration of the contents of the potato cells.
This can exist identified on the graph equally the point which shows no net movement of h2o by osmosis , which would be represented by a change in mass.
- Question
-
What is the concentration of solutes in the cells of the white potato in this investigation?
-
29%
This value is where the line crosses the x-centrality.
Percentiles
The concentration of dissolved solutes in the cells of unlike potatoes will vary slightly from white potato to spud. If nosotros have a ready of data for a range in concentrations, we tin expect at the range , and the mean - merely these do not tell united states of america whether data are evenly spread or whether they are amassed together within a certain range.
Scientists use percentiles to separate a set up of data into 100, and look to see where the data lie within these divisions.
The median is the point in a gear up of data where l per cent of the data fall above this value, and l per cent below it. This is the l th percentile.
The 75 th percentile is where 75 percent of the data autumn below this value.
In that location are several methods of finding a percentile. The simplest is the nearest rank method. As with finding the median of a gear up of data, brainstorm by putting the data into lodge.
For a range of values for the concentration of murphy cell sap:
| 0.27 | 0.32 | 0.25 | 0.24 | 0.28 | 0.31 | 0.xxx | 0.26 | 0.29 | 0.29 | 0.31 | 0.35 | 0.21 | 0.28 | 0.28 | 0.26 |
| 0.35 | 0.22 | 0.27 | 0.26 | 0.24 | 0.23 | 0.39 | 0.28 | 0.29 | 0.27 | 0.26 | 0.25 | 0.30 | 0.27 | 0.25 | 0.26 |
Arranged in order:
| 0.21 | 0.22 | 0.23 | 0.24 | 0.24 | 0.25 | 0.25 | 0.25 | 0.26 | 0.26 | 0.26 | 0.26 | 0.26 | 0.27 | 0.27 | 0.27 |
| 0.27 | 0.28 | 0.28 | 0.28 | 0.28 | 0.29 | 0.29 | 0.29 | 0.thirty | 0.30 | 0.31 | 0.31 | 0.32 | 0.35 | 0.35 | 0.39 |
To find, for example the 50 th percentile, showtime find the rank:
\[\text{ordered rank} = \frac{\text{percentile}}{100} \times \text{number of entries in data ready}\]
\[\text{ordered rank} = \frac{fifty}{100} \times 32 = 16\]
So the fifty th percentile will be the 16 thursday number in the ordered data ready, starting from the left. The 50 th percentile is 0.27.
| 0.21 | 0.22 | 0.23 | 0.24 | 0.24 | 0.25 | 0.25 | 0.25 | 0.26 | 0.26 | 0.26 | 0.26 | 0.26 | 0.27 | 0.27 | 0.27 |
| 0.27 | 0.28 | 0.28 | 0.28 | 0.28 | 0.29 | 0.29 | 0.29 | 0.30 | 0.30 | 0.31 | 0.31 | 0.32 | 0.35 | 0.35 | 0.39 |
In instances where the ordered rank is not a whole number, you should circular the number upwardly.
- Question
-
Find the 90 th percentile for the same prepare of data.
-
0.32 mol dm −iii .
\[\text{ordered rank} = \frac{\text{percentile}}{100} \times \text{number in data ready}\]
\[\text{ordered rank} = \frac{xc}{100} \times 32 = 29\]
This method will merely give percentiles as numbers that be in the information set.
In other methods, percentiles tin can exist interpolated for values that don't exist in the data set.
Source: https://www.bbc.co.uk/bitesize/guides/z22vw6f/revision/7
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