E.g: Reaction between Hydrogen and Oxygen to Produce Water
2 H2 (g) + O2 (g) -----> 2 H2O (l)
According to the equation We can get the following information
2 moles of Hydrogen gas reacts with one mole of Oxygen gas to produce 2 moles of water
Using this information try to answer the following information
i. How many moles of water will be produced by completely reacting one mole of Hydrogen?
ii. How many moles of Oxygen is required to make 4 moles of Water?
Answers:
i. 1 mole
ii. 2 moles
How can we answer the questions if the masses are given ?
We know we can calculate the moles by dividing the mass by the relative atomic mass/ relative formula mass.
we can use the following equation for the above calculation
N= M/ Mr ( number of moles= mass in grames/ Molecular or atomic mass)
1. i. How many moles of water will be produced by completely reacting 4g of Hydrogen?
ii. What would be the mass of water produced?
answer:
Number of moles of Hydrogen:
N= M/ Mr
N= 4/ 2
N= 2 moles
According to the equation ratio between Hydrogen and water is 2:2= 1:1
therefore the number of moles of water = 2 moles
ii. Using the same equation we can calculate the mass of water
N= M/ Mr
2=M/ 18
M= 36g
Next about finding the percentage by mass of an element in a compound
