# Arithmetic help in chemistry

• Andrew321
In summary, the mass of a calcium atom can be calculated by multiplying its atomic mass unit (amu) of 40.1 by the conversion factor of 1.66x10^-24g/amu and then converting from grams to kilograms. The final answer is 6.6566x10^-26kg or 6.6578x10^-26kg/atom, depending on the method used. Remembering Avogadro's number (6.02x10^23) can simplify the calculation.

#### Andrew321

ok, I'm trying to get the mass of a calcium atom in kilograms...formula for converting atoms to grams is(1.00amu=1.66x10^-24g)Calcium is 40.1amu
Ok, here is the setup with it..
40.1amu/1 x 1.66x10^-24g/1.00amu x 1kg/1,000g= ...
So how am i suposed to get the answer? Could someone please put the answer our step by step for me? Thanks a bunch

Andrew

The main thing is to get the units to work out.

40.1amu * 1.66x10^-24g/amu * 1kg/1000g = 6.6566x10^-26kg

The way we did questions like this at my school was like this:
40.08g/mol * 1mol/6.02x10^23atoms * 1kg/1000g = 6.6578x10^-26kg/atom

Both ways work but I personally like the second way better. 6.02x10^23 is avogadro's number which is fairly easy to remember since you see it a lot. That 1.66x10^-24 is 1 over avogadro's number which does the same thing in both equations but it just makes it so you need to remember another number (not a good thing).

, to get the mass of a calcium atom in kilograms, we need to use the conversion factor of 1.00amu = 1.66x10^-24g. This means that for every 1.00 atomic mass unit (amu) of calcium, there is 1.66x10^-24 grams (g).

To convert from grams to kilograms, we also need to use the conversion factor of 1kg = 1,000g. This means that for every 1 kilogram (kg), there are 1,000 grams (g).

To set up the problem, we start with 40.1amu (the atomic mass of calcium) and use the first conversion factor to cancel out the units of amu and leave us with grams. Then, we use the second conversion factor to cancel out the units of grams and leave us with kilograms.

Here is the setup:

40.1amu x (1.66x10^-24g/1.00amu) x (1kg/1,000g)

Now, we can simplify this by canceling out the units of amu and grams:

40.1 x 1.66x10^-24 x 1kg/1,000

This leaves us with the answer of 6.66x10^-23kg. So, the mass of a calcium atom is 6.66x10^-23kg.

I hope this helps! Remember, when converting units, always make sure to set up your problem with the appropriate conversion factors and cancel out units as needed.

## What is the purpose of arithmetic in chemistry?

Arithmetic is used in chemistry to perform calculations and solve problems related to chemical reactions, concentrations, and other quantitative aspects of the science.

## What are some basic arithmetic operations used in chemistry?

In chemistry, addition, subtraction, multiplication, and division are commonly used to determine quantities such as molar mass, concentration, and reaction yields.

## How can I convert between different units in chemistry?

To convert between units in chemistry, you can use dimensional analysis, where you multiply by conversion factors to cancel out unwanted units and end up with the desired unit.

## Can I use a calculator for arithmetic in chemistry?

Yes, calculators can be used for arithmetic in chemistry, but it is important to understand the equations and concepts behind the calculations in order to correctly interpret and apply the results.

## How can I check my arithmetic calculations in chemistry?

You can check your calculations by using significant figures and checking for consistent units throughout the problem. It is also helpful to double check your work and use the correct mathematical operations.