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anyanavicka [17]
3 years ago
11

A 0.125 g sample of unknown hydrocarbon is prepared for combustion analysis. After the hydrocarbon undergoes complete combustion

, 0.4225 g of CO2 and 0.0865 g of H2O are produced. What is the empirical formula of the unknown
Chemistry
1 answer:
Arturiano [62]3 years ago
8 0

Answer:

Empirical formula is CH

Explanation:

A hydrocarbon, CₐHₓ reacts with oxygen in the combustion reaction as follows:

CₐHₓ + O₂ → a CO₂ + x/2 H₂O

That means we can find the moles of C and H from the moles of CO2 and H2O. As empirical formula is defined as the simplest whole-number ratio of atoms in a molecule, we can determine it as follows:

<em>Moles CO2 = Moles C -Molar mass: 44.01g/mol:</em>

0.4225g * (1mol / 44.01g) = 0.0096 moles C

<em>Moles H2O -Molar mass: 18.01g/mol:</em>

0.0865g H2O * (1mol / 18.01g) = 0.0048moles H2O * (2mol H / 1mol H2O) =

0.0096 moles H

The ratio of atoms of C:H is:

0.0096moles C / 0.0096moles H = 1

That means empirical formula is CH

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2 years ago
A 29.8 mL sample of a 0.476 M aqueous hydrocyanic acid solution is titrated with a 0.487 M aqueous barium hydroxide solution. Wh
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Answer:

The pH is 4.76

Explanation:

Step 1: Data given

Volume of a 0.476 M hydrocyanic acid solution = 29.8 mL = 0.0298 L

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Ka HCN = 6.2 * 10^-10

Step 2: Calculate pH

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Barium hydroxide is a strong base.

 

The question asked = the pH BEFORE any base has been added, so we can ignore the base.  

 

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Ka =  [H+][CN-]/[HCN]

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Ka = [H+]²/[HCN]

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The pH is 4.76

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3 years ago
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