C1 Quick Revision Questions · C3 Quick Revision Questions C3 for AQA GCSE examination 2018 onwards H = Higher tier only SS = Separate science only

C3 Quick Revision Questions

C3 for AQA GCSE examination 2018 onwards

H = Higher tier only

SS = Separate science only

Question 1

• What is the law of conservation of mass?

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• No atoms are lost or made during a chemical reaction.

Answer 1 .... of 50


Question 2

• What is the relative atomic mass?

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• The mass of an atom relative to 1/12th of a carbon-12 atom.

Answer 2 .... of 50


Question 3

• What is the formula mass of a molecule?

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• The sum of the atomic masses of all of the atoms in a molecule.

Answer 3 .... of 50


Question 4

• Why might a reaction like decomposing a carbonate appear to violate the law of

conservation of mass?

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• The reaction gives off gas (carbon dioxide).

Answer 4 .... of 50


Question 4

• Why do reactions stop?

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• The limiting reactant is used up.

Answer 4 .... of 50


Question 5

• What is uncertainty in a measurement?

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• The range of values within which the true value of a measurement falls.

Answer 5 .... of 50


Question 6

• What is the difference between range and mean?

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Answer 6

• The range is the difference between the highest measurement and the lowest

measurement.

• The mean is the sum of the measurements divided by the number of measurements

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Question 7

• What is precision?

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Answer 7

• Precision refers to the closeness of two or more measurements to each other

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Question 8

• What are numbers of molecules measured in?

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• Moles.

Answer 8 .... of 50


Question 9

• What is Avogadro’s number?

.... of 50 H


• 6.02 x 1023

Answer 9 .... of 50


Question 10

• What is a mole?

.... of 50 H


• A standard amount of substance. One mole of any substance contains the same number of particles, atoms, molecules or ions as any other one mole.

Answer 10 .... of 50


Question 11

• How can you work out the number of moles?

.... of 50 H


• Moles = mass/molar mass



Question 12

• How is molar concentration calculated?

.... of 50 H


• Concentration = moles/volume (dm3)



Question 13

• How is mass based concentration calculated?

.... of 50 H


• Concentration = mass (g) /volume (dm3)



Question 14

• What is the equation for percentage yield?

.... of 50 SS


• %Yield = Actual Mass/Theoretical Mass

Answer 14 .... of 50 SS


Question 15

• How is atom economy calculated?

.... of 50 SS




100

reactants all ofmasses formula relative of Sum

product desiredof mass formula Relative

economy Atom

Question 16

• What is the volume of one mole of gas at room temperature and pressure?

.... of 50 SS H


• 24 dm3



Question 17

• What is the mass of three moles of KBr?

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• .1 mole of K is 39

• 1 mole of Br is 80

• 1 mole = 39+80 = 119

• 3 mole = 119 x 3 = 357



Question 18

• How many particles in two moles of helium?

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• .



2 x 6.02 x 1023 = 1.204 x 1024

Question 19 .... of 50


• How do you calculate concentration in terms of moles?

• .Concentration = no. moles ÷ volume



Question 20

• What can a titration be used to be measure?

.... of 50 SS


• .Can be used to calculate how concentrated a solution is



Question 21

• In a titration what piece of titration equipment delivers a fixed volume?

.... of 50 SS


• .A pipette delivers a fixed volume



Question 22

• What piece of equipment delivers a changing volume in a titration?

.... of 50 SS


• A burette delivers a variable volume.



Question 23

• Explain the process for a titration?

.... of 50 SS


• Fill a burette with acid, record start volume of acid

• Pipette 25cm3 of alkali into a conical flask

• Put a few drops of universal indicator into the flask

• Add the acid from the burette to the conical flask , swirl gently

• When the colour changes to neutral, record the volume of acid used to turn to neutral

Answer 23 .... of 50 SS


Question 24

• How do you find the concentration of acid?

.... of 50 SS




Concentration of alkali x volume of alkali = concentration of acid x volume of acid

Question 25

• What is the equation to calculate percentage uncertainty for a set of measurements?

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• .percentage uncertainty =

range of measurement x 100

mean



Question 26

• What is the equation to calculate the range of a set of data?

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• Range = highest measurement – lowest measurement



Question 27

• How many moles of H2O will be made when 1 mole of C3H8 react?

C3H8 + 5O2 3CO2 + 4H2O

.... of 50 H


• 4



Question 28

• How many moles of H2O will be made when 3 moles of C3H8 react?

C3H8 + 5O2 3CO2 + 4H2O

.... of 50 H


• 12



Question 29

• What mass of H2O will be made when 44g of C3H8 react? (C=12, H=1, O=16)

C3H8 + 5O2 3CO2 + 4H2O

.... of 50 H


Answer 29

• 72g

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Question 30

• What mass of H2O will be made when 220g of C3H8 react? (C=12, H=1, O=16)

C3H8 + 5O2 3CO2 + 4H2O

.... of 50 H


Answer 30

• 360g

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C1 Quick Revision Questions · C3 Quick Revision Questions C3 for AQA GCSE examination 2018 onwards H = Higher tier only SS = Separate science only