Guys i in some chemistry mole exercises please

[Giuseppe96]

1)When Mg is burned in air,a mixture of MgO and Mg3N2 is produced.If 3,6g of Mg produces 5,7g of
mixture,what is the percentage by mass of each compound in the mixture?
2)A solution of an acid having the formula H3NSO3 is prepared by dissolving 9,7g in water and making up the solution to 250ml.On titrating this solution against 0.500M potassium hydroxide,is found that 20ml alkali,requires 25ml aid for neutralisation.Determine the basicity of the acid.
I really can't understand what do i have to do in those problems of moles.Thank you in advance for your help!

 

[BvU]

Hi Giuseppe,

Here at PF we try to help folks help themselves. That's why the homework fora have a template:

Homework Statement

Homework Equations

The Attempt at a Solution

Fill in especially 2 and 3 -- it's required (see guidelines)

 

[Giuseppe96]

Hi Giuseppe,

Here at PF we try to help folks help themselves. That's why the homework fora have a template:

Homework Statement

Homework Equations

The Attempt at a Solution

Fill in especially 2 and 3 -- it's required (see guidelines)

well thank you for the answer.Regarding the first one i wrote the formula as:5Mg+O2+2N2=2MgO+Mg3N2 and if 3,6g is Mg and 5,7 is MgO+Mg3N2 i did 5,7-3,6=2,1 to find out the mass of O2+N2(maybe)...but i don t know hwo to find the masses separately.
Regarding the second one,i can't understad the part of alkali where there are the numbers 20 and 25 ml,and i can't find out the chemical reaction neither...if only i understand these i will maybe be able to solve it alone.Thank you again for your answer,hope you will reply me.

 

[Borek]

1. Assume you have x grams of MgO and y grams of Mg₃N₂. Can you express the mass of the mixture in terms of x, y? Can you express mass of Mg present in both substances in terms of x, y and relevant molar masses?

2. You can't start with the reaction equation, as it is exactly what you are asked to find. However, you can easily calculate number of moles of the base used and number of moles of the acid present. What does the ratio of the two tell?

 

[Giuseppe96]

1. Assume you have x grams of MgO and y grams of Mg₃N₂. Can you express the mass of the mixture in terms of x, y? Can you express mass of Mg present in both substances in terms of x, y and relevant molar masses?

2. You can't start with the reaction equation, as it is exactly what you are asked to find. However, you can easily calculate number of moles of the base used and number of moles of the acid present. What does the ratio of the two tell?

Thanks for the answer,can the ratio of the second one be H3NSO3:KOH=2:1?that's what I've found out...by the way i can t still understand the first one :)

 

[Borek]

Thanks for the answer,can the ratio of the second one be H3NSO3:KOH=2:1?

Show how, that's not what I got.

by the way i can t still understand the first one :)

Show what you did.

In general: "show what you did" is a key to the help at PF.