Emp Formula Zinc Chloride Web 01 02
Determination of the Empirical Formula for Zinc Chloride
Name:__________________________________________ Course______ Period:____
Prelab
Show your Calculations for the following problems
1. How many grams of sulfur would combine with 26.1 g of potassium to form K2S?
2. A 1.31g sample of sulfur was reacted with chlorine to form 4.22g of compound. What is the empirical formula of the compound?
3. 0.256g of a lanthanum oxide was decomposed and produced 0.219g of lanthanum. What is the empirical formula of the compound?
4. What is the purpose of heating the empty evaporating dish and watch glass?
5. What is the purpose of the watch glass? Why is it not necessary to know the individual masses of the evaporating dish and watch glass?
Determination of the Empirical Formula for Zinc Chloride
Objective: To experimentally determine the empirical formula for the product of the reaction between metallic zinc and hydrochloric acid by recovering the product by evaporating it to constant dry mass.
Introduction: When zinc metal is reacted with hydrochloric acid, hydrogen gas is released and an aqueous solution of zinc chloride is produced. The zinc chloride solution when evaporated to dryness leaves a pure salt product. In order to calculate the simplest whole number ratio of chlorine to zinc or empirical formula for zinc chloride, we need to use the initial mass of zinc and the solid product formed. It is important that all of the zinc used be reacted and that large excess amounts of hydrochloric acid not be used. Then, from the mass of zinc consumed and the total mass of product formed, the masses of both zinc and chlorine may be determined. Converting these to number of moles and then calculating the simplest whole number ratio, by dividing by both by the smaller of the two numbers, gives the empirical formula. If either of the numbers is non-integral, then multiply by the smallest number required to give two whole numbers as subscripts in
Name:__________________________________________ Course______ Period:____
Prelab
Show your Calculations for the following problems
1. How many grams of sulfur would combine with 26.1 g of potassium to form K2S?
2. A 1.31g sample of sulfur was reacted with chlorine to form 4.22g of compound. What is the empirical formula of the compound?
3. 0.256g of a lanthanum oxide was decomposed and produced 0.219g of lanthanum. What is the empirical formula of the compound?
4. What is the purpose of heating the empty evaporating dish and watch glass?
5. What is the purpose of the watch glass? Why is it not necessary to know the individual masses of the evaporating dish and watch glass?
Determination of the Empirical Formula for Zinc Chloride
Objective: To experimentally determine the empirical formula for the product of the reaction between metallic zinc and hydrochloric acid by recovering the product by evaporating it to constant dry mass.
Introduction: When zinc metal is reacted with hydrochloric acid, hydrogen gas is released and an aqueous solution of zinc chloride is produced. The zinc chloride solution when evaporated to dryness leaves a pure salt product. In order to calculate the simplest whole number ratio of chlorine to zinc or empirical formula for zinc chloride, we need to use the initial mass of zinc and the solid product formed. It is important that all of the zinc used be reacted and that large excess amounts of hydrochloric acid not be used. Then, from the mass of zinc consumed and the total mass of product formed, the masses of both zinc and chlorine may be determined. Converting these to number of moles and then calculating the simplest whole number ratio, by dividing by both by the smaller of the two numbers, gives the empirical formula. If either of the numbers is non-integral, then multiply by the smallest number required to give two whole numbers as subscripts in