# How to calculate the AMU?

• Indranil
In summary, the conversation is about calculating the atomic mass unit (AMU) of carbon-12. The calculation is shown as ¹²C₆ = 6.023 X 10²³, but the confusion arises when dividing 12 by the Avogadro number. The question is whether it should be 12 or 12 X 10⁻³. The solution is that it should be 12 divided by the Avogadro number, which is equal to 1.99264654 X 10⁻²⁶ grams, the mass of an atom of 12C. The confusion may have arisen due to the lack of units provided in the original calculation.

## Homework Statement

This the calculation of AMU. I don't understand the calculation. The calculation is below:
¹²C₆ = 6.023 X 10²³
12 X 10⁻3 / Avogadro number = 1.99264654 X 10⁻²⁶
Why 12 X 10⁻3 it should be only 12 / Avogadro number
I am confused. Please simplify it.

## Homework Equations

This the calculation of AMU. I don't understand the calculation. The calculation is below:
¹²C₆ = 6.023 X 10²³
12 X 10⁻3 / Avogadro number = 1.99264654 X 10⁻²⁶
Why 12 X 10⁻3 it should be only 12 / Avogadro number

## The Attempt at a Solution

¹²C₆ = 6.023 X 10²³
12 / Avogadro number = 1.99264654 X 10⁻²⁶ g

The question is set out too confusedly to know what it is.
Please try again: give quotes if there is some text that is confusing you.
12/(6.023 X 10²³) g should be the mass of an atom of 12C.
I do not know what C6 is in this context.

Last edited:
As your instructor has undoubtedly told you millions of times, units are important.

## 1. How do I calculate the atomic mass unit (AMU) of an element?

To calculate the atomic mass unit (AMU) of an element, you will need the atomic mass of each individual isotope of that element and its relative abundance. Multiply the mass of each isotope by its relative abundance, then add all of those values together to get the atomic mass unit (AMU) of the element.

## 2. What is the conversion factor for atomic mass units (AMU) to grams?

The conversion factor for atomic mass units (AMU) to grams is 1 AMU = 1.6605 x 10^-24 grams. This means that to convert from AMU to grams, you would multiply the number of AMUs by 1.6605 x 10^-24.

## 3. How do I calculate the average atomic mass of an element?

The average atomic mass of an element is calculated by taking the weighted average of all the naturally occurring isotopes of that element. This means multiplying the atomic mass of each isotope by its relative abundance, then adding all of those values together. The result is the average atomic mass of the element.

## 4. Can the atomic mass unit (AMU) of an element change?

No, the atomic mass unit (AMU) of an element is a constant value. However, the atomic mass of an element may appear to change if there is a change in the relative abundance of its isotopes.

## 5. How is the atomic mass unit (AMU) used in chemistry?

The atomic mass unit (AMU) is used in chemistry to represent the mass of atoms and molecules. It is especially useful when working with very small particles, such as atoms and subatomic particles, as their individual masses are too small to be measured in grams. The AMU allows for a more precise and convenient unit of measurement in these cases.

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