Question

what is the formula mass of calcium sulfate dihydrate caso₄·2h₂o? be sure to add the water hydration, which is the 2h₂o part (water surrounding the calcium sulfate).
○ 136 g/mol
○ 164 g/mol
○ 172 g/mol
○ 154 g/mol

Explanation:

Step1: Calculate the mass of each element

• Calcium (\(Ca\)): atomic mass \(= 40\space g/mol\)
• Sulfur (\(S\)): atomic mass \(= 32\space g/mol\)
• Oxygen (\(O\)): There are \(4\) in \(CaSO_4\) and \(2\) in \(2H_2O\), total \(6\). Atomic mass of \(O = 16\space g/mol\), so total mass from \(O=6\times16 = 96\space g/mol\)
• Hydrogen (\(H\)): There are \(4\) in \(2H_2O\). Atomic mass of \(H = 1\space g/mol\), so total mass from \(H = 4\times1=4\space g/mol\)

Step2: Sum up the masses

$$40 + 32+96 + 4=172\space g/mol$$

Answer:

172 g/mol