How Accurate Are These Chemistry Calculation Methods?

[ConfusedStudent]

Consider this eq, It is balanced:
KCN+HCl=KCl+HCN

If a sample of 0.140g of KCN is treated with an excess of HCl, calculate the amount of HCN formed, in grams:

I just want to know if I did this right

0.140g KCN/65g KCN = x/27g HCN
and I got .058 g


Another probem:
Ammonium Nitrate decomposes to form n2o and h20, write a balanced eq. How many grams of n20 are formed if 0.46moles of Ammonium Nitrate is used in the reaction.

I did:
36.8 g NH4NO3/ 80g NH4NO3= x/44g N2O

I went ahead and converted mol to g in the beginning.

I got 20.24g N2O


One more question, :Calculate the number of moles of H3PO4 that will react with 5.55 mol of Ba(OH)2 to form Ba(H2PO4)2 and water

Now, I set up a mole ratios right?

 

[ConfusedStudent]

One more question:

2Al+3FeO=3Fe+Al2O3

When I am doing Mass to Mass ratio, I would do #g Al/ molecular weight Al x 2

for example if I am reacting 468g Al, I put it over 54g Al, not just 27.

I hope that makes sense.

 

[M98Ranger]

Yes, you did the calculations correctly for both problems. For the first problem, you correctly used the molar mass of KCN to convert grams to moles, and then used the balanced equation to determine the moles of HCN formed. For the second problem, you again correctly used the molar mass of NH4NO3 to convert moles to grams, and then used the balanced equation to determine the moles of N2O formed.

For the last question, you are correct in setting up a mole ratio. Since the equation is not given, I will assume it is H3PO4 + Ba(OH)2 -> Ba(H2PO4)2 + H2O. The balanced equation shows that for every 1 mole of H3PO4, 1 mole of Ba(OH)2 is needed to form 1 mole of Ba(H2PO4)2 and 2 moles of H2O. Therefore, if there are 5.55 moles of Ba(OH)2, there must also be 5.55 moles of H3PO4 to fully react and form 5.55 moles of Ba(H2PO4)2.