Q.3.26 - An Introduction to General, Organic, and Biological Chemistry

Question

Convert each of the following energy units:

a. 8.1 kcal to cal

b. 325 J to KJ

c. 2550 cal to KJ

d. 2.5 kcal to J

Step-by-Step Solution

Answer

(part a) $8100 cal$

(part b) $0.325 kJ$

(part c) $10.7 kJ$

(part d ) $10460 J$

(Part a) Step 1: Given Information

The given value is $8.1 kcal$

To convert$\text{ 8.1 kcal to cal }$by the appropriate method

(Part a) Step 2: Explanation

For converting $\text{ 8.1 kcal}$ to calories we have-

Using $1 \mathrm{kcal}=1000 \mathrm{cal}$,

Hence for $8.1 kcal$,$8.1kcal$

 $$\begin{gathered} =8.1\times 1000 \\ =8100 cal \end{gathered}$$

(Part b) Step 3: Given Information

The given value is $325 J$

To convert $325 \mathrm{J}\text{ to kJ}$ by the appropriate method

(Part b) Step 4: Explanation

For converting $325 \mathrm{J}\text{ to kJ}$ we have-

Using,$1 \mathrm{kJ}=1000 \mathrm{J}$

Hence for $325 J$,

$$\begin{gathered} =\frac{325}{1000} \\ =0.325 kJ \end{gathered}$$

(Part c ) Step 5: Given Information

The given value is$2550 cal$

To convert$2550 \mathrm{cal}\text{ to kJ}$by the appropriate method.

(Part c) Step 6: Given Information

For converting $2550 \mathrm{cal}\text{ to kJ}$ we have,

Using $1 \mathrm{kcal}=4.184 \mathrm{kJ}$ and $1 \mathrm{kcal}=1000 \mathrm{cal}$,

Hence for $2550 cal$,

$$\begin{gathered} =2550\times \frac{4.184}{1000} \\ =10.7J \end{gathered}$$

(Part d) Step 7: Given Information

The given value is $2.5 \mathrm{kcal}$

To convert $2.5 \mathrm{kcal}\text{ to }\mathrm{J}$ using the appropriate method.

(Part d) Step 8: Given Information

For converting $2.5 \mathrm{kcal}\text{ to }\mathrm{J}$ we have,

Using $1 \mathrm{kcal}=1000 \mathrm{cal}$ and $1 \mathrm{cal}=4.184 \mathrm{J}$,

Hence for $2.5 kcal$,

$$\begin{gathered} =2.5\times 4.184\times 1000 \\ =10460 J \end{gathered}$$