Balancing chemical equations worksheet with example problems and instructions.

Let’s solve the balancing equations step by step.

---

First, let’s look at the first equation:
Mg + O₂ → MgO

Step 1: Count atoms on each side.

Left side (reactants):
- Mg = 1
- O = 2 (because O₂ means two oxygen atoms)

Right side (products):
- Mg = 1
- O = 1

→ Oxygen is not balanced! Left has 2, right has 1.

Step 2: Add a coefficient to balance oxygen.

We need 2 oxygen atoms on the right. So put a 2 in front of MgO:

Now: Mg + O₂ → 2MgO

Check again:

Right side now:
- Mg = 2 (because 2 × MgO)
- O = 2 (because 2 × O)

Left side still:
- Mg = 1
- O = 2

→ Now magnesium is unbalanced! Left has 1, right has 2.

Step 3: Fix magnesium.

Put a 2 in front of Mg on the left:

2Mg + O₂ → 2MgO

Check again:

Left:
- Mg = 2
- O = 2

Right:
- Mg = 2
- O = 2

✔ Balanced!

So for the first problem:
- Coefficient for Mg = 2
- Coefficient for O₂ = 1 (we don’t write 1, but it’s understood)
- Coefficient for MgO = 2

And atom counts:
- Mg = 2 on both sides
- O = 2 on both sides

---

Now the second equation:
Ca + O₂ → CaO

Step 1: Count atoms.

Left:
- Ca = 1
- O = 2

Right:
- Ca = 1
- O = 1

→ Oxygen is unbalanced again.

Step 2: Put a 2 in front of CaO to get 2 oxygen atoms on right:

Ca + O₂ → 2CaO

Now right side:
- Ca = 2
- O = 2

Left side:
- Ca = 1
- O = 2

→ Calcium is now unbalanced.

Step 3: Put a 2 in front of Ca on left:

2Ca + O₂ → 2CaO

Check:

Left:
- Ca = 2
- O = 2

Right:
- Ca = 2
- O = 2

✔ Balanced!

So for the second problem:
- Coefficient for Ca = 2
- Coefficient for O₂ = 1
- Coefficient for CaO = 2

Atom counts:
- Ca = 2 on both sides
- O = 2 on both sides

---

Final Answer:

For Mg + ___ O₂ → ___ MgO:
Coefficients: 2, 1, 2
Mg = 2, O = 2 on both sides

For ___ Ca + ___ O₂ → ___ CaO:
Coefficients: 2, 1, 2
Ca = 2, O = 2 on both sides