1.
State what is meant by a pure substance. [1]
JD SCIENCE
Chemical analysis
Answer all questions. Show working. Answers are in a separate file on the Worksheets page — do not look at them until you have finished.
2.
State what is meant by a formulation. [1]
3.
State what is meant by Rf value. [1]
4.
State what is meant by chromatography. [1]
5.
State what is meant by a flame test. [1]
6.
State what is meant by a cation test. [1]
7.
State what is meant by an anion test. [1]
8.
State what is meant by instrumental analysis. [1]
9.
State what is meant by a melting point. [1]
10.
State what is meant by limewater. [1]
11.
Owain is asked about a pure substance in a WJEC Chemistry paper.
(a) Describe a pure substance. [2]
(b) Explain why a pure substance is important in this topic. [3]
12.
Owain is asked about a formulation in a WJEC Chemistry paper.
(a) Describe a formulation. [2]
(b) Explain why a formulation is important in this topic. [3]
13.
Owain is asked about Rf value in a WJEC Chemistry paper.
(a) Describe Rf value. [2]
(b) Explain why Rf value is important in this topic. [3]
14.
Owain is asked about chromatography in a WJEC Chemistry paper.
(a) Describe chromatography. [2]
(b) Explain why chromatography is important in this topic. [3]
15.
Owain is asked about a flame test in a WJEC Chemistry paper.
(a) Describe a flame test. [2]
(b) Explain why a flame test is important in this topic. [3]
16.
Owain is asked about a cation test in a WJEC Chemistry paper.
(a) Describe a cation test. [2]
(b) Explain why a cation test is important in this topic. [3]
17.
Rf = 4.2 / 6.0 [3]
18.
A solvent front is 8.0 cm and Rf is 0.25. How far did the spot travel? [3]
19.
How many ions are tested if five flame colours are recorded? [3]
20.
A solution gives a white ppt with acidified BaCl₂. Which ion? [3]
21.
A solution gives a cream ppt with AgNO₃ that dissolves in concentrated NH₃. Which halide? [3]
22.
Percentage purity if 9.6 g of product contains 9.12 g of the pure compound [3]
23.
Owain carries out a WJEC-style required practical linked to chemical analysis. This is a typical WJEC required-practical style question.
(a) Identify the independent variable and the dependent variable. [2]
(b) State one control variable and explain why it must be controlled. [2]
(c) Suggest one improvement or source of error and how it affects the result. [2]
24.
Owain carries out collecting valid data for chemical analysis. This is a typical WJEC required-practical style question.
(a) Identify the independent variable and the dependent variable. [2]
(b) State one control variable and explain why it must be controlled. [2]
(c) Suggest one improvement or source of error and how it affects the result. [2]
25.
Owain carries out drawing a graph for chemical analysis. This is a typical WJEC required-practical style question.
(a) Identify the independent variable and the dependent variable. [2]
(b) State one control variable and explain why it must be controlled. [2]
(c) Suggest one improvement or source of error and how it affects the result. [2]
26.
Owain carries out evaluating a method about chemical analysis. This is a typical WJEC required-practical style question.
(a) Identify the independent variable and the dependent variable. [2]
(b) State one control variable and explain why it must be controlled. [2]
(c) Suggest one improvement or source of error and how it affects the result. [2]
27.
Compare a pure substance with a formulation. [4]
28.
Compare a formulation with Rf value. [4]
29.
Compare Rf value with chromatography. [4]
30.
Compare chromatography with a flame test. [4]
31.
Apply your knowledge of an anion test to this situation: HCl + limewater; BaCl₂; AgNO₃ [3]
32.
Apply your knowledge of instrumental analysis to this situation: faster, more accurate, sensitive [3]