Homework Help

[Shordaay]

1. N₂ (g) + 3H₂ (g) --> 2NH₃

(i)what volume of hydrogen (R.T.P) is needed to react exactly with 2.8kg of N₂?
(ii). what mass if ammonia would be produced assuming that r*n was complete?
(iii). what mass of ammonium nitrate fertilizer could be made from this amount of ammonia?

2. copper (II) nitrate can be prepared by adding copper(II) oxide to nitric acid. what is the maximum mass of copper (II) nitrate which can be formed from 150cm3 of nitric acid of concentration 0.5mol/dm-3?

3. what mass of potassium hydrogen carbonate must be added to sulphuric acid to produce 8.7g of potassium sulphate?

4. 50cm3 of an acid with formula HnX and concentration 0.4mol/dm-3 are needed to neutralize 100cm3 of potassium carbonate solution of cone 13.8g/dm-3. calculate the value of n in HnX.

[KriggY]

Did you try it at least? Seems that most ppl here dont even try to solve those homeworks - no offence.

anyway:
1)
i+ii) count amount of moles of nitrogene and then you can calculate amount of moles of hydrogen needed and amount of amona created -
iii) what fertilizer exactly? NH₄NO₃? write an equation of creating NH₄NO₃ and then calculate it from amount of NH₃ you have use simple cross-multiplication

2) write an equation of forming Cu(NO₃)₂ and from amount of HNO₃ you have calculate amount of CuO needed. You have 1.5dm3 of 0.5 mol/dm3 HNO₃ which means 0.75 mole of HNO₃

3) write and equation of forming K₂SO₄ and how many moles of K₂SO₄ 8.7 grams are and then from that amount of moles calculate mass of KHCO₃

4) im not sure about this one sorry

[Shordaay]

yes i did try them.. the only one i didnt try was the last one and a and b of number 1.. im not sure if what i did to get d answer was correct

[Shordaay]

thank you for ur help btw

[GrahamKemp]

4.) 50cm3 of an acid with formula HnX and concentration 0.4mol/dm-3 are needed to neutralize 100cm3 of potassium carbonate solution of cone 13.8g/dm-3. calculate the value of n in HnX.

(Note: K2CO3 ~ 138 g/mol)
(Note: ... and of course 1000cm^3 = 1 dm^3 = 1 L)

The neutralisation of potassium carbonate in acid will follow the general formula:
2 HnX + n K2CO3 = 2 KnX + n CO2 + n H2O

For every n mole of K2CO3 we need 2 mole of HnX.
Ie: The ratio of HnX:K2CO3 should reduce down to 2:n.

So: From the given volumes, concentrations, and weights, you just need to find the ratio of moles of each reactant.