1.
State what is meant by relative formula mass. [1]
JD SCIENCE
Key concepts in chemistry
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 mole. [1]
3.
State what is meant by conservation of mass. [1]
4.
State what is meant by a limiting reactant. [1]
5.
State what is meant by concentration. [1]
6.
State what is meant by yield. [1]
7.
State what is meant by atom economy. [1]
8.
State what is meant by a balanced equation. [1]
9.
State what is meant by an empirical formula. [1]
10.
State what is meant by Avogadro's constant. [1]
11.
Devon is asked about relative formula mass in a Edexcel Chemistry paper.
(a) Describe relative formula mass. [2]
(b) Explain why relative formula mass is important in this topic. [3]
12.
Devon is asked about a mole in a Edexcel Chemistry paper.
(a) Describe a mole. [2]
(b) Explain why a mole is important in this topic. [3]
13.
Devon is asked about conservation of mass in a Edexcel Chemistry paper.
(a) Describe conservation of mass. [2]
(b) Explain why conservation of mass is important in this topic. [3]
14.
Devon is asked about a limiting reactant in a Edexcel Chemistry paper.
(a) Describe a limiting reactant. [2]
(b) Explain why a limiting reactant is important in this topic. [3]
15.
Devon is asked about concentration in a Edexcel Chemistry paper.
(a) Describe concentration. [2]
(b) Explain why concentration is important in this topic. [3]
16.
Devon is asked about yield in a Edexcel Chemistry paper.
(a) Describe yield. [2]
(b) Explain why yield is important in this topic. [3]
17.
Calculate Mr of CaCO₃ (Ca=40, C=12, O=16). [3]
18.
How many moles in 9 g of NaOH (Mr=40)? [3]
19.
What mass of 0.25 mol of H₂O (Mr=18)? [3]
20.
A solution is 0.20 mol/dm³ and has volume 250 cm³. How many moles of solute? [3]
21.
2Na + 2HCl → 2NaCl + H₂. What mass of H₂ from 4.6 g Na (Aᵣ 23)? [3]
22.
Actual yield 8.0 g, theoretical 10.0 g. Percentage yield? [3]
23.
Devon carries out a titration of acid with alkali. This is a typical Edexcel 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.
Devon carries out making a soluble salt from an acid and an insoluble base. This is a typical Edexcel 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.
Devon carries out measuring mass change when Mg burns or CaCO₃ is heated. This is a typical Edexcel 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.
Devon carries out preparing a standard solution. This is a typical Edexcel 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 percentage yield with atom economy. [4]
28.
Compare a concentrated solution with a dilute solution. [4]
29.
Compare an empirical formula with a molecular formula. [4]
30.
Compare a closed system with an open system. [4]
31.
Apply your knowledge of atom economy to this situation: less waste [3]
32.
Apply your knowledge of a balanced equation to this situation: mole ratios come from the equation [3]