Upon oxidation of 6.6 g of aldehyde with copper hydroxide (bivalent), 21.6 g of a red-brown

| June 15, 2021 | education

Upon oxidation of 6.6 g of aldehyde with copper hydroxide (bivalent), 21.6 g of a red-brown precipitate were formed. What is the formula for the starting aldehyde?

Let us compose the equation for the oxidation reaction of aldehyde in the presence of copper (II) hydroxide.

R –COOH + 2Cu (OH) 2 → R – COOH + Cu2О ↓ + H2O.

Let’s find the amount of the substance aldehyde.

n = m: M.

М (R –COH) = х + 29 g / mol.

n = 6.6 g: (x + 29) g / mol.

Let’s find the quantitative ratios of substances.

Aldehyde and copper (I) oxide are in quantitative ratios of 1: 1.

Therefore, the amount of copper oxide substance and aldehyde will be the same.

M (Cu2O) = 64 × 2 + 16 = 144 g / mol.

Let’s find the amount of substance Cu2O.

n = 21.6: 144 g / mol = 0.15 mol.

Let’s make a proportion.

6.6: (x + 29) = 0.15.

x + 29 = 6.6: 0.15

x + 29 = 44,

x = 44 – 29,

x = 15.

Find the molecular weight of the acid.

15 + 29 = 44

29 g / mol – carbonyl group – СОН.

The remainder is made up of carbon and hydrogen atoms.

СН3 –СОН – acetaldehyde.

Answer: acetaldehyde (acetaldehyde).



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