Stoichiometry IGCSE 0654 - Part 1

The relative formula mass, M_r, of calcium carbonate, CaCO₃, is 100.

What is the mass of carbon present in 100 g of calcium carbonate?

• 12 g

• 40 g

• 36 g

• 60 g

The compound magnesium nitrate has the formula Mg(NO₃)₂.

What is the relative formula mass of magnesium nitrate?

• 86

• 134

• 148

• 172

Propane burns in oxygen.

C₃H₈ + xO₂ → 3CO₂ + yH₂O

Which values of x and y balance the equation?

• x = 5, y = 4

• x = 7, y = 4

• x = 10, y = 8

• x = 13, y = 8

Tags

NGSS.HS-PS1-7

• A

• B

• C

• D

Tags

NGSS.HS-PS1-7

Calcium phosphate contains phosphate ion, PO₄^3-.

What is the formula for calcium phosphate?

(You do not need to subscript the numbers)

(a)  

Carbon Dioxide has the molecular formula of CO₂. The total relative molecular mass of CO₂ is 44. What percentage of CO₂ is made up by oxygen?

• 32.1%

• 64.2%

• 72.7%

• 50.0%

1 mole of sodium hydroxide (NaOH) has a mass of 40g. What is the mass in 0.15 mole of NaOH?

• 0.4g

• 4g

• 12g

• 6g

1 mole of lithium has 6.022 x 10²³ atoms of lithium. How many atoms of lithium is there in 0.25 mole of lithium?

• 6.022 x 10²³ atoms

• 3.011 x 10²³ atoms

• 1.505 x 10²³ atoms

• 1.200 x 10²³ atoms

1 mole of Na has 23g. How many atoms of Na is in 1 mole of Na?

• 6.022 x 10²³ atoms

• 4.011 x 10²³ atoms

• 3.022 x 10²³ atoms

• 1.505 x 10²³ atoms

What is the mass of oxygen needed to oxidise 21g of lithium?

4Li + O₂ ----> 2Li₂O

• 32g

• 21g

• 24g

• 16g