Chemistry HELP!!!?

Question

1) Ammonia (NH3) is widely used as a fertilizer
and in many household cleaners.
How much ammonia is produced when
3:76 mol of hydrogen gas react with an ex-
cess of nitrogen gas? Answer in units of mol.

2) The decomposition of potassium chlorate
(KClO3) is used as a source of oxygen in the
laboratory.
How much potassium chlorate is needed to
produce 15 mol of oxygen? Answer in units of
mol.

3) The elements lithium and oxygen react explo-
sively to from lithium oxide (Li2O).
How much lithium oxide will form if 1:5 mol
of lithium react? Answer in units of mol.

4) The disinfectant hydrogen peroxide (H2O2)
decomposes to form water and oxygen gas.
How much O2 will result from the decom-
position of 2:89 mol of hydrogen peroxide?
Answer in units of mol.

5) Acetylene gas (C2H2) is produced as a result
of the reaction
CaC2(s) + 2H2O(`) !
C2H2(g) + Ca(OH)2(aq) :
If 15 g of CaC2 are consumed in this reac-
tion, how much H2O is needed? Answer in
units of mol.

Answer 1

wow... you really do know your chemistry - sorry again, can't help you but I wish you ALLLLLLL the best, and must say the folks who answered - if they are infact correct, very nice.

good luck in whatever you are trying to figure out.

Answer 2

1) 1.25 mol NH3
2) 5.0 mol KClO3
3) 0.75 mol Li2O
4) 1.46 mol O2
5) 0.47 mol H2O

Each of these problems are found by converting the moles of what is given to the moles of the unknown.
#1-3 are found from the chemical formula
---Eg: #1= They give you the mols of Hydrogen, you want mols of ammonia. For every one mole of ammonia there is three moles of hydrogen, hence NH3.
#1
3.76mols H x (1 mol NH3 / 3 mol H) = 1.25 mol NH3

#4 & 5 are found from the chemical equation.
---Eg: #4= They tell you that H2O2 decomposes to form water and oxygen. So you can write the chemical equation:
2H2O2 ---> 2H2O + O2(Balanced)
so you are given moles of H2O2 and want to find moles of O2.
for every mole of O2 there is 2 moles of H202.
#4
2.89 mols H2O2 x (1 mol O2 / 2 mols H2O2) = 1.45 mol O2

The only difference with #5 is you have to convert grams of CaC2 to moles of CaC2 by using the molar mass.

Answer 3

#1
How much ammonia NH3 is produced when
3:76 mol of hydrogen gas react with an excess of nitrogen gas? Answer in units of mol.

Hydrogen and Nitrogen gas atoms travel in covalently bonded pairs. H2 and N2.

Unbalanced reaction: 3.76 Mol H2 +N2 --> NH3
Balance the equation.
3H2+N2=2(NH3)
The ratio of Hydrogen needed to Nitrogen needed is 3 moles Hydrogen go to produce 2 Moles of Ammonia. Simple.
(2/3)*3.76Mol =
2.50666 --> 2.51 Mol Ammonia

- - - -
) The decomposition of potassium chlorate
(KClO3) is used as a source of oxygen in the
laboratory. How much potassium chlorate is needed to
produce 15 mol of oxygen
Unbalanced KClO3 --> KCl + O2
Balanced: 2( KClO3) --> 2( KCl) + 3O2
Three moles of Oxygen are produced for each 2 Moles of KClO3.
15 Moles Oxygen * ( 2 Moles KClO3 per 3 Moles Oxygen) = Moles KClO3.
Notice that the equation above was setup so that the units would cancel out. ie Moles Oxygen * Moles KClO3 / Moles Oxygen.
Note the units of Moles Oxygen appear on the top and bottom, and cancel out leaving Moles KClO3.

So (15 Moles Oxygen * 2Moles KClO3) / (3 Moles Oxygen ) -->
= 10 Moles KClO3
From the balanced equation we can check our work.
Balanced: 2( KClO3) --> 2( KCl) + 3O2
Balanced: 5 * [ 2( KClO3) --> 2( KCl) + 3O2 ]

Balanced: (2*5)( KClO3) --> (2*5)( KCl) + (3*5)O2

Balanced: 10( KClO3) --> 10( KCl) + 15O2

Still true.

- - - - - -
3) The elements lithium and oxygen react explo-
sively to from lithium oxide (Li2O).
How much lithium oxide will form if 1:5 mol
of lithium react? Answer in units of mol.

Unbalanced: Li + O2 --> Li2O
Balanced: 4Li +O2 --> 2 (Li2O )
So 2 Moles Lithium Oxide is produced per 4 Moles of Lithium metal.
Setup the equation again, so that the units cancle out.
1.5M Lithium * ( 2 M Lithium Oxide / 4 M Lithium ) = 0.75 M Lithium Oxide.
Note again, that the units of Lithium apppear on the top and bottom of the equation, and cancle out leaving units of Lithium Oxide.
Check your work.
Balanced: 4Li +O2 --> 2 (Li2O )
UnBalanced: (1.5M) Li + O2 --> (Li2O )
UnBalanced: (6M) Li + O2 --> (Li2O )
( I just used the balanced formula and multiplied Lithium by 4 to keep the same ratio ).
UnBalanced: (6M) Li + O2 --> 3(Li2O ) (balanced Lithium)
Balanced: (6M) Li + (1+1/2)O2 --> 3(Li2O )
the equation is balanced, but the oxygen 1 and a half could be written as 3/2, or I will multiply the whole equation by 2, so that 3/2 becomes 3. [ ( 3/2) * 2= 6/2 = 3 ]
Balanced: (12M) Li + (3)O2 --> 6(Li2O )
Ok, it is balanced using the 1.5 M Lithium. Now divide every term by the same number so that Lithium is 1.5.
12/1.5 is 8. So divide the whole balanced equation by 8.
Balanced: (12/8 M) Li + (3/8)O2 --> 6/8(Li2O )
And you can see, that 1.5M Li --> 3/4 M Li2O ( 3/4=0.75 )
Balanced: (1.5M) Li + (3/8)O2 --> 3/4(Li2O )
So as noted above, 1.5M Li --> 0.75 M Li2O

- - - - - - -
4) The disinfectant hydrogen peroxide (H2O2)
decomposes to form water and oxygen gas.
How much O2 will result from the decom-
position of 2:89 mol of hydrogen peroxide?
Answer in units of mol.
unbalanced: H2O2 --> H2O + O2
balanced: 2(H2O2) --> 2 H2O + O2
Same as the first two questions.
One mole of Oxygen is produced per 2 Moles of Hydrogen Peroxide
2.89 M H202 * ( 1 O2 per 2 M H2O2) --> 1.445 Moles O2
1.45 M O2 rounded up to 2 decimal places.

- - - - - -
5) Acetylene gas (C2H2) is produced as a result
of the reaction
CaC2(s) + 2H2O -->C2H2(g) + Ca(OH)2(aq) :
If 15 g of CaC2 are consumed in this reac-
tion, how much H2O is needed? Answer in
units of mol.
Calcium Carbide is 64.1 grams per mole. Just look on the periodic chart in the link below.
Calcium is 40.08, Carbon is 12.01.
So Calcium Carbide:
CaC2 is 40.08+ 2(12.01) = 64.1 grams per mole.

So, if you have 15 grams of Calcuim Carbide, how many Moles is that? Remember to make sure your units cancle out.
You need your answer in Moles.

So you will divide grams by grams per mole.
( 15 grams CaC2 ) / (64.1 grams / Mole )= 0.234 M CaC2

Remember fractions (A/B )/(C/D) = (AD) / (BC)
So (grams/1)/(grams/Mole)= (grams * Mole)/( 1 *grams) = Mole
because the grams cancle from top and bottom.

Back to the problem,
From the balanced equation
CaC2(s) + 2H2O -->C2H2(g) + Ca(OH)2(aq) :
It can be seen that for every mole of CaC2, 2 M of H2O are needed.
You determined that you have 0.234 M CaC2, so you need twice that much of H2O
You need 0.468 M H2O to complete the reaction.
Because they only gave you 2 significant digits in the 15g CaC2, you should round this answer to 0.47 M H2O.


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