How many joules of heat must be added to melt a 75-g block iron if it required 12.2 Calories?

Question

Quizplus · Accepted Answer

First, we need to convert 12.2 Calories to joules.

1 Calorie = 4.184 J

Therefore,

12.2 Calories = 12.2 x 4.184 J = 51.02048 J ≈ 5.10 x 10^1^0 J

Next, we use the formula:

q = m x ΔHf

where q is the heat required, m is the mass of the substance, and ΔHf is the heat of fusion for the substance.

The heat of fusion for iron is 6.06 x 10^3 J/kg.

Therefore,

q = (75 g / 1000) kg x 6.06 x 10^3 J/kg = 0.4545 x 10^3 J = 4.545 J

We see that 5.10 x 10^10 J is the closest answer choice, so our final answer is:

Answer: E

How Many Joules of Heat Must Be Added to Melt