**– Calculate the mass (in grams) of 5.20 x 1014 molecules of adrenaline, C9H13NO3.**

**– A particular oral contraceptive contains 0.0409 mg ethynyl estradiol in each pill. The formula of this compound is C20H24O2.**

a) How many moles of ethynyl estradiol are there in one pill?

b) How many molecules is this?

**– How many carbon atoms are in a 0.0409 mg sample of ethynyl estradiol?**

a) What mass of carbon is this?

**– A chemist places 2.99 g of sodium carbonate in a 250.0 mL volumetric flask and fills it to the mark with water. Calculate the concentrations of the major ionic species in units of mol/L (M).**

a) Sodium ion concentration?

b) Carbonate ion concentration?

**– Concentrated ammonia is 14.8 M. What volume of this solution should be used to prepare 1.85 L of 0.500 M NH3?**

**– Hydrogen fluoride is produced industrially by the action of sulphuric acid on CaF2. Suppose 278 kg of CaF2 is treated with an excess of sulphuric acid and 127 kg of HF is produced.**

a) What is the percent yield of HF? In percent

b) How much CaF2 remains unreacted? In kg

**– If the oxidation reaction is 76.5 % efficient, what mass of cyclohexane is required to produce 3.43 kg of adipic acid? Answer in kg**

**– How many atoms of each kind are represented in the formula Ni(ClO4)2? Name the elements present.**

a)What do the parentheses mean? Are there three groups or should you multiply by the subscript of the parentheses?

b)How many ClO4 groups are there?