The mass of acetaldehyde formed upon hydration of 7.8 g of acetylene in the presence of a mercury salt.

Let’s make the equation:
С2Н2 + Н20 = Н2С = СНОН = Н3С – СОН – the hydration reaction occurs in the presence of the HgCL2 salt, an intermediate product of vinyl alcohol is formed, then, after its isomerization, acetaldehyde is released;
M (C2H2) = 26 g / mol;
M (C2H4O) = 44 g / mol;
Determine the number of moles of acetylene, if the mass is known:
Y (C2H2) = m / M = 7.8 / 26 = 0.3 mol;
The number of moles according to the equation of acetylene and acetaldehyde are equal to 1 mole, which means that Y (C2H4O) = 0.3 mole;
Let’s calculate the mass of acetaldehyde:
m (C2H4O) = Y * M = 0.3 * 44 = 13.2 g.
Answer: the mass of acetaldehyde is 13.2 g.