1) A fictitious element X has an average atomic mass of 122.199 u.122.199 u. Element X has two naturally occuring isotopes. The most abundant isotope has an isotopic mass of 121.825 u121.825 u and a relative abundance of 62.99%.62.99%. Calculate the isotopic mass of the least abundant isotope.

2) A 14.599 g14.599 g sample of CaCl2CaCl2 was added to 12.147 g12.147 g of K2CO3K2CO3 and mixed in water. A 3.571 g3.571 g yield of CaCO3CaCO3 was obtained.

What is the limiting reagent?

a) CaCO3CaCO3

b) K2CO3K2CO3

c) CaCl2CaCl2

Calculate the percent yield of CaCO3.CaCO3.

yield of CaCO3=CaCO3= ?

3) The first step in the reaction of AlkaSeltzer with stomach acid consists of one mole of sodium bicarbonate (NaHCO3)(NaHCO3) reacting with one mole of hydrochloric acid (HCl)(HCl) to produce one mole of carbonic acid (H2CO3),(H2CO3), and one mole of sodium chloride (NaCl).(NaCl).

Using this chemical stoichiometry,

i)determine the number of moles of carbonic acid that can be produced from 33 mol NaHCO3NaHCO3 and 77 mol HCl.

ii)Which of the two reactants limits the number of moles of H2CO3H2CO3 that can be made?

a)NaHCO3NaHCO3

b)HCl

iii)How much excess reactant remains after the reaction?