STOICHIOMETRY IGCSE

Calcium phosphate contains phosphate ion, PO₄^3-.

What is the formula for calcium phosphate?

(You do not need to subscript the numbers)

An oxide of nitrogen has the following composition by mass: N, 30.4%; O, 69.6%.

It has a relative molecular mass of 92.

What is the molecular formula of the oxide of nitrogen?

(Ar N=14, O=16)

• N₂O₃

• NO₂

• N₂O₄

• NO

Tags

NGSS.HS-PS1-2

NGSS.HS-PS1-3

Propane burns in oxygen.

C₃H₈ + xO₂ → 3CO₂ + yH₂O

Which values of x and y balance the equation?

• x = 4, y = 5

• x = 5, y = 4

• x = 2, y = 4

• x = 3, y = 4

Tags

NGSS.HS-PS1-7

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

Ar Ca=40, C=12, O=16.

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

Tags

NGSS.HS-PS1-7

Phosphorus forms another compound with hydrogen with the following composition by mass:

P: 93.94%, H: 6.06%

Calculate the empirical formula of the compound. (Ar P=31, H=1)

(You do not need to subscript the numbers)

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

What is the relative formula mass of magnesium nitrate?

(Ar Mg=24, N=14, O=16)

Which statements are correct?

(Ar Ca=40, C=12, O=16, H=1, Cl=35.5)

• 1 and 2

• 2 and 4

• 1 and 3

• 2 and 3

Tags

NGSS.HS-PS1-7

• A

• B

• C

• D

Tags

NGSS.HS-PS1-7

• A

• B

• C

• D

Tags

NGSS.HS-PS1-7

• A

• B

• C

• D

Tags

NGSS.HS-PS1-7