Question

7.   Consider the balanced equation:

2A + 5B ↔ 3C + D

0.32 mol A are mixed with 1.02 mol B at an elevated temperature. After 0.21 mol of A are left, how much B is left? Hint given in feedback.

8. Balance the following chemical reaction using smallest whole numbers:

C₃H₈(g) + O₂(g) --> CO₂(g)+ H₂O(g)

What is the number of CO₂ molecules in the balanced equation?

9. What is the number of H₂O molecules in the balanced equation?

10

What is the number of O₂ molecules in the balanced equation?

11. Balance the following chemical reaction using smallest whole numbers:

CuO(s) +NH₃(g) --> Cu(s) + N₂(g) + H₂O(g)

Hint, balance the elements in the following order--nitrogen, hydrogen, oxygen, and copper.

What is the number of Cu atoms in the balanced equation?

12. What is the number of nitrogen molecules in the balanced equation? (Refer to the previous question)

13.   What is the number of water molecules in the balanced equation? (Refer to previous questions)

Answer 1

7

2A + 5B ↔ 3C + D

from equation it is evident that if 2 moles of a reacts in reaction then 5 moles of B is required

So for 1 mole of A, 5/2 mole of B will react

initially concentration of A = 0.32 mol

initial concentration of B = 1.02 mol

final concentration of A = 0.21 mol

number of moles of A reacted = 0.32 -0.21 = 0.11 mol

number of moles of B wll react = 0.11 x 2.5 = 0.275 moles

since 0.275 moles of B is reacted then number of moles of B left = 1.02 -0.275 = 0.745 moles

8) C₃H₈(g) + O₂(g) --> CO₂(g)+ H₂O(g)

to balance this,

First balance carbon on right side

C₃H₈(g) + O₂(g) --> 3 CO₂(g)+ H₂O(g)

Now balance hydrogen on both sides

C₃H₈(g) + O₂(g) --> 3CO₂(g)+ 4H₂O(g)

now balance oxygen as per equation

C₃H₈(g) + 5O₂(g) -->3 CO₂(g)+4 H₂O(g)

Number of CO₂ molecule in balanced equation = 3

9) number of H₂O molecule = 4

10)number of O₂molecule = 5

11) CuO(s) +NH₃(g) --> Cu(s) + N₂(g) + H₂O(g)

first balance nitrogen on left side

CuO(s) +2NH₃(g) --> Cu(s) + N₂(g) + H₂O(g)

now balance hydrogen

CuO(s) +2NH₃(g) --> Cu(s) + N₂(g) + 3H₂O(g)

now balance oxygen,

3CuO(s) +2NH₃(g) --> Cu(s) + N₂(g) + 3H₂O(g)

now balance copper

3CuO(s) +2NH₃(g) -->3 Cu(s) + N₂(g) +3 H₂O(g)

number Cu atoms = 3

12)Number of nitrogen molecule = 1

13)number of water molecule = 3