For the reduction of 43.5 g of aldehyde, 0.75 mol of hydrogen was spent. Indicate the formula for the aldehyde.

According to the condition of the problem, we schematically write down the reduction of an unknown aldehyde:
RCOH + H2 = R – OH – reduction reaction, alcohol was obtained;
According to the reaction equation, the number of moles of aldehyde and hydrogen are equal to -1 mol, which means that Y (RCOH) = 0.75 mol;
We calculate the molar mass of the aldehyde by the formula:
M (RCOH) = Y * M = 0.75 * 43.5 = 32.62 g / mol;
General formula of aldehydes: CnH2n + 1COH;
CnH2n + 1COH = 32.62 g / mol;
12n + 2 + 1 + 12 + 16 + 1 = 32.62;
12n = 0.62, n = 0.05;
Molecular formula: НСОН, M (HCOH) = 1 * 2 + 12 + 16 = 30 g / mol.
Answer: the formula for the aldehyde is NSOH (methanal).