Stoichiometry Calculation

The equation below represents the reaction to extract aluminium from aluminium oxide.

2Al₂O₃ -------- 4Al + 3O₂

What is the mass of aluminium that can be extracted from 102 g of aluminium oxide?

[Relative atomic mass: O, 16; Al,27]

• 13.5 g

• 27.0 g

• 54.0 g

• 108.0 g

XCO₃ ---------- XO + CO₂

The equation above shows the action of heat on the carbonate salt of metal X.

How many moles of XCO₃ are needed to produced 4.0 g of oxide X?

[Relative atomic mass: C, 12; O, 16; X, 64]

• 0.03

• 0.05

• 0.08

• 0.09

Tags

NGSS.HS-PS1-7

Sulphuric acid used as an electrolyte in a car battery has a concentration of 0.5 mol dm^-3.

How many moles of sulphuric acid is there in 100 cm^3?

• 0.025

• 0.05

• 0.1

• 0.5

Diagram 1 shows the set-up of apparatus for the titration of potassium hydroxide solution with sulphuric acid.

What is the total volume of the mixture in the conical flask at the end point of the titration in Diagram 1if the concentration of sulphuric acid is 1.0 moldm^-3 ?

• 10 cm³

• 20 cm³

• 30 cm³

• 40 cm³

Which of the following quantities of substance contain 6 x 10²² molecules?

[Relative atomic mass: H, 1; C, 12; O, 16; Avogadro’s Constant: 6 X 10²³ mol ^-1]

I 1.8 g water

II 1.0 g hydrogen gas

III 3.2 g oxygen gas

IV 4.4 g carbon dioxide

• I and II only

• III and IV only

• I, III, and IV only

• I, II, III, and IV

The equation below represents the decomposition of hydrogen peroxide solution.

2H₂O_2(aq) ----------- 2H₂O_(l) + O_2(g)

Which of the following are produced when 1 mole of hydrogen peroxide is decomposed completely?

[1 mole of gas occupies 24 dm³ at room condition;

Avogadro’s Constant: 6.0 X 10²³ mol^-1]

I 2 moles of water

II 12 dm³ of oxygen gas

III 3 x 10²³ of oxygen molecules

IV 1.2 x 10²⁴ of water molecules

• I and III only

• I and IV only

• II and III only

• II and IV only

What is the number of molecules in 1 mole of ammonia, NH₃?

Use the information that the Avogadro constant = 6.0 x 10²³ mol^-1

• 1.5 X 10²³ molecules

• 6.0 X 10²³ molecules

• 1.2 X 10²⁴ molecules

• 2.4 X 10²⁴ molecules

A compound with formula X₂CO₃ has a relative formula mass of 138. What is the relative atomic mass of X?

Use the information that the relative atomic mass of C = 12 and O = 16.

• 39

• 69

• 78

• 110

The equation shows the reaction between sulphuric acid and sodium hydroxide.

H₂SO₄ + 2NaOH ---------- Na₂SO₄ + 2H₂O

What is the volume of 1.0 mol dm^-3 sodium hydroxide solution which can neutralize 25.0 cm³ of 1.0 mol ^-3 sulphuric acid?

• 12.5 cm³

• 25.0 cm³

• 50.0 cm³

• 75.0 cm³

3.2 g of cooper(II) oxide powder is reacted with excess dilute nitric acid.

What is the mass of cooper(II) nitrate formed in the reaction?

Use the information that the relative atomic mass of N = 14, O = 16 and Cu = 64.

• 3.76 g

• 4.96 g

• 5.04 g

• 7.52 g