Homework Question..... (1 Viewer)

[AnAn]

it is desired to determine the concentration of hydrochloric acid in a brick-cleaning solution. samples(each25mL) of the acid solution are to be titrated with a standard sodium carbonatesolution.

1) describe how to prepare 500mLof 0.500 mol L solution of sodium carbonate from pure dosium carbonate decahydrate crystals. Give precise details including the mass of crystals to be used.

2) Give a reason for not using solid sodium hydroxide directly to prepare a standard solution for titration with hydrochloric acid

3) when making a standard solution, why is the water added to the solid and not the other way around?

thx for help^^

 

[Xayma]

Well 1 is maths and I cant be bothered getting my calc.

2) NaOH is hydroscopic, it will abosrb water from the atmosphere making weighing it accurately near impossible, therefore not knowing how many moles there are.

3) You will need water to rinse all of the solid in and to make sure it doesnt leave parts behind on the neck of the bottle/beaker etc.

If you added it to the water you will have to add extra water, distorting the concentration.