OCR Chemistry A - 'Amount of Substance' 2.1.1 b-d

Fill in the blanks:

Empirical formula is the ________ _____ _______ _____ of atoms of each element in a compound.

(a)  

In an experiment, 1.203g of calcium combines with 2.13g of chlorine to form a compound. Work out the empirical formula.

[A_r: Ca = 40.1, Cl = 35.5]

• CaCl

• Ca₂Cl

• CaCl₃

• CaCl₂

Chemical analysis of a compound gave the percentage composition by mass C: 40.00%; H: 6.67%; O: 53.33%. The relative molecular mass of the compound is 180.0. Determine the molecular formula.

[A_r: C = 12.0; H = 1.0; O = 16.0]

• CH₂O

• C₂H₂O

• C₅H₁₂O₆

• C₆H₁₂O₆

A nickel compound has the formula Ni(NO₃)₂.xH₂O and a molar mass of 290.7 g mol^-1. Calculate the value of x.

(a)  

What is the empirical formula of C₁₂H₂₁O₆?

(a)  

An organic compound has the composition by mass:

C = 53.33%; H = 11.11%; O = 35.56%

What is the empirical formula of the organic compound

• C₄H₈O₂

• C₄H₁₀O₂

• C₂H₄O

• C₂H₅O

• A

• B

• C

• D

• A

• B

• C

• D

7.45 g of hydrated sodium sulfate, Na₂SO₄.xH₂O, is heated until it loses all of its water. It’s new mass is found to be 4.56 g. What is the value of x?

(a)  

When 5.00g of crystals of hydrated tin (II) chloride, SnCl₂.xH₂O, are heated, 4.20g of anhydrous tin (II) chloride are formed. Calculate the number of molecules of water of crystallisation are in SnCl₂.xH₂O

(a)