Moles to Compounds Conversion Worksheet with a Key - Free Printable

Let's solve each problem step by step, using the appropriate concepts from chemistry, especially focusing on Avogadro's number and mole conversions.

---

Avogadro's Number:

- $ 1 \text{ mole} = 6.022 \times 10^{23} \text{ particles (atoms, molecules, etc.)} $

We'll use this to convert between moles and number of particles.

---

## Problem 5: How many atoms are there in 0.085 atoms of carbon (C)?

This question is confusing because it says "0.085 atoms" — but you can't have a fraction of an atom in reality. Atoms are discrete entities. So if you have 0.085 atoms, that would be less than one atom.

But if we interpret this as a typo or misunderstanding, and assume they meant 0.085 moles of carbon, then:

> But based on what's written:
> "How many atoms are there in 0.085 atoms of carbon?"

Answer:
There are 0.085 atoms — because it's already given in atoms.

But this doesn't make sense in practical terms.

✔ Likely intended: "How many atoms are there in 0.085 moles of carbon?"

Let’s assume that was the intention.

So:
$$
\text{Number of atoms} = \text{moles} \times N_A = 0.085 \times 6.022 \times 10^{23}
$$

$$
= 5.1187 \times 10^{22} \text{ atoms}
$$

✔ Answer (if corrected): $ \boxed{5.12 \times 10^{22}} $ atoms of C (rounded to 3 sig figs)

But since the original says 0.085 atoms, the answer is simply:
There are 0.085 atoms.

⚠️ This is likely a typo. We’ll proceed assuming it's 0.085 moles.

---

## Part II: Convert molecules to moles

Use:
$$
\text{Moles} = \frac{\text{Number of molecules}}{6.022 \times 10^{23}}
$$

---

Problem 6: How many moles are in $9.772 \times 10^{22}$ molecules of KOH?

$$
\text{Moles} = \frac{9.772 \times 10^{22}}{6.022 \times 10^{23}} = 0.1622 \text{ moles}
$$

✔ Answer: $ \boxed{0.162} $ moles (3 sig figs)

---

Problem 7: How many moles in $8.0 \times 10^{25}$ molecules of KMnO₄?

$$
\text{Moles} = \frac{8.0 \times 10^{25}}{6.022 \times 10^{23}} = 1.328 \times 10^2 = 132.8 \text{ moles}
$$

✔ Answer: $ \boxed{133} $ moles (3 sig figs)

---

Problem 8: How many moles in $2.37 \times 10^{23}$ molecules of H₂O₂?

$$
\text{Moles} = \frac{2.37 \times 10^{23}}{6.022 \times 10^{23}} = 0.3934 \text{ moles}
$$

✔ Answer: $ \boxed{0.393} $ moles (3 sig figs)

---

Problem 9: How many moles in $4 \times 10^{24}$ molecules of H₂S?

Note: $4 \times 10^{24}$ has 1 significant figure.

$$
\text{Moles} = \frac{4 \times 10^{24}}{6.022 \times 10^{23}} = 6.64 \times 10^0 = 6.64 \text{ moles}
$$

But with 1 sig fig: $ \boxed{7} $ moles

✔ Answer: $ \boxed{7} $ moles

---

Problem 10: How many moles in $1.005 \times 10^{19}$ molecules of Cu(NO₃)₂?

$$
\text{Moles} = \frac{1.005 \times 10^{19}}{6.022 \times 10^{23}} = 1.668 \times 10^{-5} \text{ moles}
$$

✔ Answer: $ \boxed{1.67 \times 10^{-5}} $ moles (3 sig figs)

---

## Part III: Mixed Problems

Problem 11: How many atoms are in 0.044 moles of Zn?

$$
\text{Atoms} = \text{moles} \times N_A = 0.044 \times 6.022 \times 10^{23}
$$

$$
= 2.64968 \times 10^{22} \text{ atoms}
$$

✔ Answer: $ \boxed{2.65 \times 10^{22}} $ atoms (3 sig figs)

---

Problem 12: How many moles are in $6.39 \times 10^{22}$ atoms of H?

$$
\text{Moles} = \frac{6.39 \times 10^{22}}{6.022 \times 10^{23}} = 0.1061 \text{ moles}
$$

✔ Answer: $ \boxed{0.106} $ moles (3 sig figs)

---

## ✔ Final Answers Summary:

| Problem | Answer |
|--------|--------|
| 5 | Likely typo: If 0.085 moles, then $ \boxed{5.12 \times 10^{22}} $ atoms |
| 6 | $ \boxed{0.162} $ moles |
| 7 | $ \boxed{133} $ moles |
| 8 | $ \boxed{0.393} $ moles |
| 9 | $ \boxed{7} $ moles |
| 10 | $ \boxed{1.67 \times 10^{-5}} $ moles |
| 11 | $ \boxed{2.65 \times 10^{22}} $ atoms |
| 12 | $ \boxed{0.106} $ moles |

---

💡 Key Concept Recap:
- Use Avogadro's number ($6.022 \times 10^{23}$) to convert between moles and particles.
- Moles = Particles / Avogadro’s number
- Particles = Moles × Avogadro’s number
- Pay attention to significant figures!

Let me know if you'd like these formatted for printing or explanation in class!