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Edexcel IAL Chemistry 3.P7 Plotting and interpreting graphs

Put the independent variable on x, label both axes with units, use most of the grid and draw one justified line or curve before reading or comparing features.

Syllabus
First assessment 2019
Course
Chemistry YCH11
Level
AS

Exam points

  • Plot points accurately with labelled axes, units, sensible scales and a best-fit line.
  • Sketch an expected curve from rate behaviour and show the correct final plateau.
  • Use gradient, intercept, extrapolation or anomalous points to extract practical meaning.

3.P7—Plotting and interpreting graphs question 1

[Maximum number: 4]

Precipitation reactions can be used to determine the formulae of compounds.
A bottle has a torn label which shows that it contains a nitrate with the formula X(NO_3)_2.

Figure for Question 3.P7—Plotting and interpreting graphs question 1 — Edexcel A-Level Chemistry AS

Procedure
- a technician dissolved a sample of 12.41 g of the nitrate in deionised water to make 100 cm^3 of solution
- the technician pipetted 5.0 cm^3 of 1.50 mol dm^-3 potassium iodide into each of a series of test tubes
- each test tube then had a volume of the nitrate solution added to it as shown in the table
- a cloudy yellow solution formed, and the precipitate was allowed to settle
- the height of the precipitate was then measured.

The equation for the reaction is

X(NO3)2(aq)+2KI(aq)→XI2( s)+2KNO3(aq)\mathrm{X}\left(\mathrm{NO}_{3}\right)_{2}(\mathrm{aq})+2 \mathrm{KI}(\mathrm{aq}) \rightarrow \mathrm{XI}_{2}(\mathrm{~s})+2 \mathrm{KNO}_{3}(\mathrm{aq})

The results of the experiment are shown.

Table for Question 3.P7—Plotting and interpreting graphs question 1 — Edexcel A-Level Chemistry AS

Question (a)

(a)

Plot the data on the grid.

Figure for Question (a) — Edexcel A-Level Chemistry AS
[ 2 ]

Question (b)

(b)

Determine the minimum volume of nitrate solution needed to react completely with 5.0 cm^3 of potassium iodide solution. You must show your working on the graph.

[ 2 ]
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