Soap in hard water

Each calcium ion in hard water takes two soap molecules out as scum, calcium stearate. You will find the soap wasted and the scum made for an amount of calcium, and the soap lost in a bucket of water. Then the program draws the soap wasted against the calcium.

The idea. $2\,\text{C}_{17}\text{H}_{35}\text{COONa} + \text{Ca}^{2+} \rightarrow (\text{C}_{17}\text{H}_{35}\text{COO})_2\text{Ca} + 2\,\text{Na}^+$. Soap is $306\ \text{g/mol}$, and the scum is $606\ \text{g/mol}$.

Your tasks.

1. In soap_wasted, return the grams of soap lost to an amount of calcium, in moles.
2. In scum, return the grams of scum made.
3. Find bucket, the soap lost in $12\ \text{L}$ of water with $0.004\ \text{mol}$ of calcium in each litre.