Question

Question #49d33

Answer 1

You need to multiply the ratios times `2` in order to get the lowest whole number ratio of `3:2`.

Explanation:

The ratios must be whole numbers. When they are not whole numbers, you need to multiply the ratios by some whole number that will give you the lowest whole number ratio. In this case, `2×1.5=3` and `2×1=2`. So the number that when multiplied will give the lowest whole number ratio is `2`, and the ratio will be `3:1` rather than `1.5:1`.

Answer 2

We know that the molar mass of `Mg` is `24.305 g*mol^(-1)`
And that the molar mass of `O` is `15.999 g*mol^(-1)`

Which means that assuming we have `100g` of compound we have

`m_(Mg) = 50.32 g`
`m_(O) = 49.68 g`

Passing it to moles

`n_(Mg) = (50.32 g)/(24.305 g*mol^(-1)) =2.070 mol`
`n_(O) = (49.68 g)/(15.999 g*mol^(-1)) =3.105 mol`

Dividing it by the smallest

`Mg rarr 2.070/2.070 = 1`
`O rarr 3.105/2.07 = 1.5` = 3/2

Multiplying both numbers by 2 to make them integers, we get `Mg_2O_3`