Question

balance the following equation:
_ c₃h₈ + _ o₂ → _ co₂ + _ h₂o
your answer

how many grams of h₂o are produced when 11.4 grams h₂ react with excess o₂?
unbalanced equation
h₂ + o₂ → h₂o
your answer

write the formula for dinitrogen tetroxide. *
your answer

write the formula for silver chromate. *
your answer

Explanation:

Step1: Balance the first equation

• Carbon atoms: In \(C_3H_8\), there are 3 carbon atoms. So, we put 3 in front of \(CO_2\) (since each \(CO_2\) has 1 carbon atom).
• Hydrogen atoms: In \(C_3H_8\), there are 8 hydrogen atoms. Each \(H_2O\) has 2 hydrogen atoms, so we put 4 in front of \(H_2O\) (\(8\div2 = 4\)).
• Oxygen atoms: On the right - hand side, in \(3CO_2\) there are \(3\times2=6\) oxygen atoms and in \(4H_2O\) there are \(4\times1 = 4\) oxygen atoms. So, total oxygen atoms on the right - hand side are \(6 + 4=10\). Each \(O_2\) has 2 oxygen atoms, so we put 5 in front of \(O_2\) (\(10\div2=5\)).

The balanced equation is \(1C_3H_8+5O_2
ightarrow3CO_2 + 4H_2O\).

Step2: Balance the second equation (\(H_2+O_2

ightarrow H_2O\))

• Oxygen atoms: Each \(O_2\) has 2 oxygen atoms and each \(H_2O\) has 1 oxygen atom. To balance oxygen, we put 2 in front of \(H_2O\).
• Hydrogen atoms: After putting 2 in front of \(H_2O\), there are 4 hydrogen atoms. Each \(H_2\) has 2 hydrogen atoms, so we put 2 in front of \(H_2\).

The balanced equation is \(2H_2+O_2
ightarrow2H_2O\).

• Molar mass calculations:
• Molar mass of \(H_2\): \(M_{H_2}=2\space g/mol\) (since \(H\) has an atomic mass of \(1\space g/mol\) and \(H_2\) has 2 \(H\) atoms).
• Molar mass of \(H_2O\): \(M_{H_2O}=(2\times1 + 16)=18\space g/mol\)
• Moles of \(H_2\): \(n_{H_2}=\frac{m_{H_2}}{M_{H_2}}=\frac{11.4\space g}{2\space g/mol}=5.7\space mol\)
• From the balanced equation \(2H_2+O_2

ightarrow2H_2O\), the mole ratio of \(H_2\) to \(H_2O\) is \(1:1\). So, moles of \(H_2O\) produced \(n_{H_2O}=5.7\space mol\)

• Mass of \(H_2O\) produced: \(m_{H_2O}=n_{H_2O}\times M_{H_2O}=5.7\space mol\times18\space g/mol = 102.6\space g\)

Step3: Write the formula for Dinitrogen tetroxide

• The prefix "di -" means 2 and "tetra -" means 4. For nitrogen (\(N\)) and oxygen (\(O\)), the formula is \(N_2O_4\)

Step4: Write the formula for silver chromate

• Silver (\(Ag\)) has a charge of \(+1\) (\(Ag^+\)). Chromate ion (\(CrO_4^{2 -}\)) has a charge of \(- 2\). Using the criss - cross method (to balance the charges), the formula is \(Ag_2CrO_4\)

Answer:

1. \(1C_3H_8+5O_2

ightarrow3CO_2 + 4H_2O\)

1. \(102.6\space g\) of \(H_2O\)
2. \(N_2O_4\)
3. \(Ag_2CrO_4\)