quantitative Chemistry, medium

Question 1

Phoebe measures out 2g of solid sodium hydroxide into a conical flask.
a) how many moles are these?
She adds 20 cm3 of water.
b) what is the concentration?

Answer 1

a) 0.05 moles,

b) 2.5 moles/dm3

Question 2

Randeep has a solution of 0.4 moles/dm3 of sulphuric acid. How many moles of acid are in 50 cm3 of this solution?

Answer 2

0.02 moles

Question 3

John wants to make a 2.5 moles/dm3 solution of copper sulphate (CuSO4 . 5H2O). How much of the anhydrous salt does he have to add to 150cm3 of water?

Answer 3

93.75g

Question 4

You have the following reaction:
Fe2O3 + 3CO = 2Fe + 3CO2
If you want to make 25 moles of iron, how many moles of iron oxide will you need to weigh out?

Answer 4

12.5 moles

Question 5

You have the following reaction:
Fe2O3 + 3CO = 2Fe + 3CO2
If you want to make 25 moles of iron, how many moles of carbon dioxide will you produce?

Answer 5

37.5 moles

Question 6

At room temperature you have 150cm3 of oxygen gas in a sealed flask. How many moles is this if the molar volume is 24?

Answer 6

0.00625moles or 6.25x10^-3

Question 7

You need 50 moles of carbon dioxide gas for a big experiment. How much volume will this occupy, if the molar volume is 24?

Answer 7

1200dm3

Question 8

You do a titration of potassium hydroxide with sulphuric acid. The equation for this is:
2KOH + H2SO4 = K2SO4 + 2H2O
If you have calculated that you have 0.2 moles of H2SO4, how many moles of KOH do you need to completely neutralise the acid?

Answer 8

0.4 moles

Question 9

You have carried out the following displacement reaction:
2NaI + Br2 = 2NaBr + I2
a) If you had 3000g of NaI how many moles is this?
b) How many moles of I2 (iodine) would you get?
c) What is the mass of iodine you would get?

Answer 9

a) 20 moles
b) 10 moles
c) 2540g or 2.54kg

Question 10

You neutralise lithium hydroxide with phosphoric acid according to the following equation:
3LiOH + H3PO4 = Li3PO4 + 3H2O
If you produce 9 moles of Li3PO4 (lithium phosphate) how many moles of lithium hydroxide will you need?

Answer 10

27 moles

Question 11

You neutralise lithium hydroxide with phosphoric acid according to the following equation:
3LiOH + H3PO4 = Li3PO4 + 3H2O
If you have 0.6 moles of lithium hydroxide, how many moles of H3PO4 (phosphoric acid) will you need?

Answer 11

0.2 moles

Question 12

You neutralise lithium hydroxide with phosphoric acid according to the following equation:
3LiOH + H3PO4 = Li3PO4 + 3H2O
a) if you had 0.6 moles of lithium hydroxide in 0.02dm3 in a flask and neutralised it completely with phosphoric acid, how many moles of Li3PO4 would you get?
b) what would be the concentration of Li3PO4 solution in 0.02dm3?

Answer 12

a) 0.2 moles

b) 10 moles/dm3

Question 13

2NaOH + H2SO4 = Na2SO4 + 2H2O
Calculate the unknown concentration of H2SO4.
a) In a conical flask you have 25cm3 of sodium hydroxide
of 2moles/dm3. How many moles of NaOH is this?
b) how many moles of H2SO4 do you need to neutralise the NaOH?
c) You add exactly 18.75cm3 of H2SO4 to neutralise the NaOH. What is the concentration of H2SO4?

Answer 13

a) 0.05 moles
b) 0.025 moles
c) 1.33 moles/dm3