Question

Алкин масой 2.7 г полностью прореагировал с 2.24 л бромоводорода (н. у.). Найти молекулярную формулу.

Answer 1

CnH2n-2 + 2HBr = CnH2nBr2

1 моль         2моля

n(HBr) = V/Va = 2,24 / 22,4 = 0,1 моля

n(CnH2n-2) = n(HBr)/2 = 0,1 / 2 = 0,05 моля

M = m/n = 2,7 / 0,05 = 54 г/моль

M(CnH2n-2) = 12*n + 2*n - 2 = 14*n - 2

14*n - 2 = 54

n = 56 / 14 = 4

C4H6

Answer 2

To find the molecular formula of the alkyne, we need to determine the balanced chemical equation for the reaction between the alkyne and bromine. Here's the balanced chemical equation for the reaction:

CₙHₘ + (n + 1)Br₂ → nCₙHₘBr₂

Given: Mass of alkyne (CₙHₘ) = 2.7 g Volume of bromine (Br₂) = 2.24 L (at normal conditions, n.u.) Bromine is in excess, so we consider only the alkyne in the reaction.

Step 1: Calculate the number of moles of the alkyne. Molar mass of alkyne (CₙHₘ) = molar mass of carbon (C) + 2 * molar mass of hydrogen (H) Molar mass of C = 12.01 g/mol Molar mass of H = 1.01 g/mol Molar mass of CₙHₘ = 12.01 g/mol + 2 * 1.01 g/mol Molar mass of CₙHₘ = 14.03 g/mol

Number of moles of CₙHₘ = Mass of alkyne (2.7 g) / Molar mass of CₙHₘ (14.03 g/mol) Number of moles of CₙHₘ = 0.1922 moles

Step 2: Determine the molecular formula. The molecular formula shows the ratio of atoms in a molecule. To find it, we need additional information about the number of carbon and hydrogen atoms in the alkyne. Unfortunately, the provided data does not include this information. Without knowing the number of carbon and hydrogen atoms, we cannot determine the exact molecular formula.

To proceed, we need to know the percentage composition of carbon and hydrogen in the alkyne or additional information about the structure of the alkyne (e.g., whether it is a simple alkyne like ethyne with two carbon atoms or a more complex one with multiple carbon atoms).

Please provide more information about the alkyne's structure or the percentage composition of carbon and hydrogen so that we can determine its molecular formula accurately.