Question

A cheeseburger from a fast food restaurant contains 19 g of fat, 20 g of carbohydrate, and 28 g of protein. how many kcal of energy does the cheeseburger contain? (the accepted caloric values for foods are 4.0 kcal/g for carbohydrate, 9 kcal/g for fat, and 4 kcal/g for protein.) report the answer to 2 significant figures.

Answer 1

Answer:

Energy content of the cheeseburger = 360 Kcal

Explanation:

Given:

Amount of fat =  19 g

Carbohydrate = 20 g

Protein = 28 g

Caloric value for fat = 9.0 kcal/g

carbohydrate = 4.0 kcal/g

Protein = 4 kcal/g

To determine:

The energy content of the cheeseburger

Calculation:

Energy content of 19 g of fat present in the burger = $\frac{19 kcal*9 g}{1 g} = 171 kcal$

Energy content of 20 g of carbs present in the burger = $\frac{20 kcal*4 g}{1 g} = 80 kcal$

Energy content of 28 g of protein present in the burger = $\frac{28 kcal*4 g}{1 g} = 112 kcal$

Total energy content = 171 + 80 + 112 = 363 kcal

In terms of 2 significant figures, the energy = 360 kcal.

Here, the trailing zero is not significant hence the important/significant digits are 3 and 6.

Answer 2

We simply get the sum of the product of each mass and caloric values.

Total energy = 19 g * 9 kcal / g + 20 g * 4 kcal / g + 28 g * 4 kcal / g

Total energy = 363 kcal

 

Rounding of f to 2 significant fig:

Total energy = 360 kcal