I am a parent who just read this in my daughter math book I am lost can someone help me in the right dirrection.


A chemical formula shows the ratio of atoms in a substance. The formula for carbon dioxide is CO2. This means carbon dioxide has 1 atom of carbon (C) for every 2 atoms of oxygen (O). Write the ratio of hydrogen (H) atoms to oxygen atoms in the substances in parts (a) and (b) below.

a. water, H2O
b. disinfectant, H2O2
c. Reasoning Ammonia has a ratio of 1 atom of nitrogen (N) to 3 atoms of hydrogen. What is the chemical formula?

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What the problem is asking for here is a ratio of one thing to the next.

For CO2 as given in the problem, we are told that there is 1 carbon and 2 oxygen which means the ratio of carbon to oxygen is 1 to 2 or 1:2

The small number to the lower right of the chemical symbol is called a subscript. It indicates the number of atoms of that element present in the compound. If there is no subscript present there is only one of them.

Use this information to help you.

For part A the process is the same as the example.

For part B the process is the same as the example.

For part C all you have to do is reverse engineer this process.

A.2 hydrogen for every 1 oxygen

B.1 hydrogen for every 2 oxygen (or 1 H for 1 O)

For a chemical formula, the letters stand for elements. For example: H is Hydrogen
A chemical formula can also have two letters. For example: Al is Aluminium. Notice the 2nd letter is lower case. That means it is joined with the previous letter. So, to count the number of elements, Count the uppercase letters.

The number after letters tell you the amount of that atom in each molecule. For example: H2O means 2 hydrogen, 1 Oxygen (if there is no number behind a letter or pair of letters, it means 1 atom)

So, to mix it all together, if I have AlH2O3 (I made this formula up, it wouldn't necessarily make anything that would be common to us) , it means I have 1 Al (aluminium), 2 H (Hydrogen), and 3 O (Oxygen)

So, for part C. NO3 (1 Nitro. 3 hydro.)

If you have any questions, feel free to ask. I went a little fast.

So, for part C. NO3 (1 Nitro., 3 hydro.)

That would be NH3

Opps, yes you are right. I had a bit of a mix up. I was mixed up with what I previously stated.