Answer to Question #174380 in General Chemistry for Nithushan Krishnanandashankary

Question

Quantities in Chemical Reactions

1. Ricardo states that for the process of iron reacting with sulfur to produce iron (III) sulfide according to

16 Fe(s) + 3 S8(s) → 8 Fe2S3(s),

16.0 g of iron will react with 3.00 g of sulfur in the reaction to produce 8.00g of iron (III) sulfide. Is Ricardo's

reasoning correct? Explain your answer.

2. A magnesium compound is made up of magnesium and another element. It contains 72.2% magnesium by mass

and the rest is made up by the other element. If the molar mass of the compound is 100.95 g/mol, identify the

other element.

3. Sodium hydroxide is commonly called caustic soda, and is used in many household drain cleaners. It is prepared

by the reaction:

calcium hydroxide + sodium carbonate → sodium hydroxide + calcium carbonate

a) Write the balanced equation for the reaction.

b) What is the maximum mass of sodium hydroxide that could be produced from 195 g of calcium hydroxide?

Answer 1

1 . Ricardo reasoning is wrong.

The limiting reagent is S8

so 3S8 =8Fe2S3

3g Sul[hur = (8 x 88 x 3)/(3 x 256.5) Fe2S3

= 2.74g Fe2S3

2 . % of element = 100-72.2 = 27.8

27.8% x 100.95 = 28.06

since the valency of magnesium is =2 , then the atomic mass will be 28/2 =14 which is nitrogen gas

therefore, the formula of the compound is Mg₃N₂

3 a . Ca(OH)₂ + Na₂CO_3 = 2NaOH + CaCO₃

b. Mass of NaOH = (2 x 40 x 195)/ 74 = 210.81 g NaOH