On a separate sheet of paper, write a complete solution to each of the problems
ID: 518629 • Letter: O
Question
On a separate sheet of paper, write a complete solution to each of the problems below. Follow the procedure outlined in class. Be sure to circle your final answer. Calculate the number of moles of potassium chlorate, KClO_3 (s), that must decompose to produce potassium chloride, KCl (s), and 1.8 moles of oxygen gas. In a single displacement reaction, magnesium metal reacts with hydrochloric acid to produce magnesium chloride and hydrogen gas. How many moles of hydrochloric acid are needed to completely react with 2.43 g of magnesium?
Explanation / Answer
Given reaction is
2 KClO3 ------> 2 KCl + 3 O2
2 moles 2 moles 3 moles
Given 1.8 moles of O2
for 3 moles of O2 to be produced from 2 moles of KClO3
for 1.8 moles of O2 has to be produced 1.8 * 2/3 = 1.2 moles of KClO3 Answer
Mg + 2 HCl -----> MgCl2 + H2
1 mole 2 moles 1moles 1mole
given 2.43 g of Mg
molar mass of Mg = 24.3 g/mol
No. of moles of Mg = Mass / molar mass = 2.43 g / 24.3 g/mol = 0.1 moles
1 moles of Mg requires 2 moles of HCl
so 0.1 mole of Mg requires 0.2 moles of HCl
Answer 0.2 moles of HCl