Question

How many moles of iron are contained in 1.75 kg of iron? A) 3.13 × 10⁻² B) 3.13 × 10⁻⁴ C) 31.3 D) 3.13 × 10⁴ E) none of the above

Answer 1

The number of moles of iron in 1.75 kg is approximately 31.3 moles. Therefore, the correct answer is C) 31.3.

To find the number of moles in 1.75 kg of iron, use the molar mass of iron. The molar mass of iron is approximately 55.85 grams per mole (g/mol). First, convert the mass given to grams:

1.75 kg = 1750 grams

Now, use the molar mass to find the number of moles

Number of moles = Mass / Molar mass

Number of moles = 1750 g / 55.85 g/mol ≈ 31.35 moles

Rounded to three significant figures, the number of moles of iron in 1.75 kg is approximately 31.3 moles. Therefore, the correct answer is C) 31.3.

Answer 2

The correct option is e.

There are approximately 31.34 moles of iron in 1.75 kg of iron. None of the provided answer choices (A, B, C, D, E) is exact, as the closest choice, C, is a rounded approximation of the actual value.

To calculate the number of moles of iron in 1.75 kg of iron, you can use the formula:

Number of moles = Mass (in grams) / Molar mass (in g/mol)

1. Find the molar mass of iron (Fe):

The molar mass of iron (Fe) is approximately 55.85 g/mol.

2. Convert the mass from kilograms to grams:

1.75 kg = 1,750 grams

3. Now, use the formula to calculate the number of moles:

Number of moles = 1,750 g / 55.85 g/mol

4. Calculate the number of moles:

Number of moles ≈ 31.34 moles

So, there are approximately 31.34 moles of iron in 1.75 kg of iron.

The closest answer choice is 31.3. However, the actual answer is approximately 31.34 moles, so none of the provided answer choices is exactly correct.