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When 1 mol of methane is burned at constant pressure, −890 kJ/mol of energy is released as heat. If a 4.19 g sample of methane is burned at constant pressure, what will be the value of ∆H? (Hint: Convert the grams of methane to moles. Also make sure your answer has the correct sign for an exothermic process.) Answer in units of kJ.

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Answer:

∆H = -233 kJ

Explanation:

Methane is CH₄, the molar mass are: 12 g/mol of C + 4x1 g/mol of H = 16 g/mol.

The number of moles is the mass divided by the molar mass:

n = 4.19/16

n = 0.261875 mol

1 mol of CH₄ -------------- -890 kJ

0.261875 mol ------------ x

By a direct simple three rule:

x = -233 kJ

∆H is negative because it's an exothermic reaction, and the system lost heat.

The value of the enthalpy change (∆H) is; -233.1 kJ

What is the Change in Enthalpy?

Formula for number of moles of Methane CH₄ is;

n = Mass/Molar Mass

Molar mass of methane = 16 g/mol

We are given mass = 4.19 g Thus;

n = 4.19/16

n = 0.261875 mol

Since 1 mol of CH₄ is gives of energy at -890 kJ

Then;

0.261875 mol of CH₄ gives;

∆H = 0.261875 * -890 = -233.1 kJ

Read more about enthalpy change at; https://brainly.com/question/14047927

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