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If 9g of aluminum reacts with 35.5g of chlorine, the empirical formula of the compound formed is A1C13

Analysing Substances - Quantitative

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Analyzing substances forms a major part of Chemistry in high school. This quiz is all about quantitative analysis. This kind of analysis allows us to identify the amounts of different elements present in compounds.

1.
What is the relative formula mass of copper sulfate CuSO4?
160 amu
96 amu
128 amu
144 amu
amu = atomic mass units
2.
What is the relative formula mass of MgF2?
60 amu
62 amu
43 amu
64 amu

Mg = 24 amu, F = 19 amu, remember that there are 2 F atoms in the molecule of MgF2

3.
What % mass of magnesium oxide is magnesium?
60%
40%
30%
70%
First you work out the relative formula mass of magnesium oxide (MgO) then divide the relative atomic mass of magnesium by the relative formula mass and multiply by 100 for the percentage
4.
What is the % mass of hydrogen in methane CH4?
20%
25%
75%
12.5%
Use the same method as for the previous question
5.
Calcium reacts with oxygen as shown by this reaction 2Ca + O2 → 2CaO. What mass of oxygen will react with 60g of calcium?
12g
24g
6g
14g
From the equation, you find that they react in a ratio of 2 moles to 1 mole. 60g of calcium is 1.5 moles so you will need 0.75 moles of oxygen molecules
6.
Sodium hydroxide reacts with chlorine to make bleach as shown by this reaction. 2NaOH + Cl2 → NaOCl + NaCl + H2O. If we have a solution containing 100g of sodium hydroxide, how much chlorine gas should we pass through the solution to make bleach?
28.65g
82.45g
88.75g
86.57g

Ratio of sodium hydroxide to chlorine is 2 moles to1 mole

7.
If 9g of aluminum reacts with 35.5g of chlorine, what is the empirical formula of the compound formed?
AlCl
AlCl2
AlCl3
Al3Cl
Use moles! One third of a mole of aluminum atoms react with 1 mole of chlorine atoms therefore there are three times as many chlorine atoms involved. Remember, the mole is nothing more complicated than a measure of the number of particles in a reaction
8.
A compound contains 13.5g of calcium, 10.8g of oxygen and 0.675g of hydrogen. What is its empirical formula?
CaOH
CaOH2
CaO2H
Ca(OH)2
It's those moles again ...
9.
A reaction that could theoretically produce 200g of product only produces 140g. What is its % yield?
70%
14.2%
142%
7%
Divide the actual yield by the theoretical yield and multiply by 100
10.
Ammonium nitrate NH4NO3 is used as a fertilizer. What is the % mass of nitrogen in it?
21%
37%
17.5%
35%
Divide the total relative atomic mass of the nitrogen in the formula by the relative formula mass and multiply by 100
Author:  Kate Gardiner