C3d - Reacting masses

Question 1

What is the relative atomic mass(3)

Answer 1

Number of protons + neutrons

Above the atomic symbol in the periodic table

Largest number shown for each element

Question 2

How do you show mass is conserved in a reaction(3)

Answer 2

use relative formular mass and a balanced symbol equation
-add up relative formular mass, taking into account the molar ratio
-show that the reactants’ mass =
products’ mass

Question 3

Why is mass conserved in a chemical reaction

Answer 3

no atoms are created or destroyed in chemical reactions

Question 4

What is the mass of the product directly proportional to

Answer 4

the mass of the limiting reactant used

Question 5

What mass of O 2 reacts with 192g of magnesium(O = 16, Mg = 24)(3)

Answer 5

2Mg + O2 —> 2MgO

2x24 + 32 —>2MgO

32/48(amount of oxygen to react with 1 gram of magnesium) x 192 = 128g

Question 6

What mass of sulfur trioxide is formed from 96g of sulfur dioxide(S = 32, O = 16)(3)

Answer 6

2SO2 + O2 —> 2SO3

128 + 32 —> 160

160/128(how much sulfur trioxide is formed from 1 gram of sulfur dioxide) x 96 = 120g

Question 7

What mass of copper carbonate is needed to make 20g of copper oxide(Cu = 64, C = 12, O = 16)(3)

Answer 7

CuCO3 —> CuO + CO2

124 —> 80 + CO2

80/124(amount of CuCO3 needed to make 1 gram of CuO) x 20 = 12.9g