Question

The "Chemistry in Focus" segment Burning Calories discusses calories in food. If a food is said to contain 350 calories per serving, determine this value in terms of joules.

Short answer

The value of 350 calories in terms of joules can be determined by multiplying 350 calories by the conversion factor 4.184 J/cal. Thus, the food contains \(350 \times 4.184 = 1464.4\) Joules of energy per serving.

Step-by-step solution

Identify the given information.

We are given that there are 350 calories per serving of the food.

Use the conversion factor between calories and joules.

We know that 1 calorie is equal to 4.184 joules.

Set up the conversion equation.

Multiply the number of calories (350) by the conversion factor (4.184 J/cal) to get the energy in joules: Energy (Joules) = Calories × Conversion factor

Perform the calculation.

Energy (Joules) = 350 calories × 4.184 J/cal = 1464.4 Joules

Write the final answer.

The food contains 1464.4 Joules of energy per serving.

Key concepts

Energy Conversion in Chemistry

When we talk about energy conversion in chemistry, we often refer to the process of changing one form of energy into another within a chemical context. This can be in the form of heat, light, or electrical energy. The concept is vital for understanding various chemical reactions and processes, such as combustion in calories burning.

For instance, when you consume food, your body metabolizes it and converts the chemical energy stored within into kinetic energy for movement and thermal energy to maintain body temperature. The calorie is a unit that measures the amount of energy in food, commonly used in nutrition. But in chemistry and physics, energy is frequently measured in joules, which is a part of the International System of Units (SI). Thus, converting calories to joules is essential in scientific studies to maintain consistency, compare values and communicate results universally.

Scientific Units of Measurement

Understanding scientific units of measurement is key to interpreting and comparing scientific data accurately. These units are standardized, which means scientists and educators around the world can understand and replicate experiments and studies. Two main types of units are used globally: the International System of Units (SI) and the Imperial system.

In the context of energy, the joule (J) is the SI unit, named after James Prescott Joule. It is defined as the amount of energy transferred when a force of one newton is applied over a distance of one meter. On the other hand, a calorie is a non-SI unit of energy typically used to express the amount of energy in food. Since scientific communication largely relies on SI units, performing conversions like calories to joules is essential for clarity and consistency in reporting results.

Nutritional Energy Values

When discussing nutritional energy values, calories are the currency of energy that we use to quantify the energy that food provides to our bodies. Technically, the 'calorie' used on food labels is actually a kilocalorie (1000 calories), the energy needed to raise the temperature of 1 kilogram of water by 1 degree Celsius.

However, energy within the body and in scientific research is often discussed in joules. This is a reflection of the body’s metabolic process, which involves converting the chemical energy from food into energy that the cells use for daily function and activity. Understanding the conversion between calories and joules is a fundamental concept that allows us to relate everyday nutritional information with scientific measurements and study the metabolism and energy consumption at a molecular level.