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3 years ago

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The combustion of 5.00 grams of c2h6(g), at constant pressure releases 259 kj of heat. what is δh for the reaction: 2c2h6(g) + 7

o2(g) => 4co2(g) + 6h2o(l)?

1 answer:

Vlad1618 [11]3 years ago

7 0

The molar mass of C2H6 is 28 g/mol, so the number of moles is:

moles C2H6 = 5 / 28 = 0.179 mol

From the equation, there are 2 moles of C2H6, therefore the heat of reaction is:

δh = (259 kj / 0.179 mol) * 2 mol

<span>δh = 2900 kJ = 2.9 MJ</span>

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How do you convert between the mass and the number of moles of a substance?

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To convert from grams to moles, you divide the number of grams by the molar mass To convert from moles to grams, you multiply by the molar mass. You must first calculate the molar mass of the substance

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3 years ago

The AE of a system that releases 12.4 J of heat and does 4.2 J of work on its surroundings It is_______ jA. 16.6 B. 12.4 C. 4.2

andre [41]

ANSWER

EXPLANATION

Given that

The energy released by the system is 12.4J

Work done on the surrounding is 4.2J

Follow the steps below to find the change in energy

In the given data, energy is said to be released to the surroundings

Recall, that exothermic reaction is a type of reaction in which heat is released to the surroundings. Hence, change in enthalpy is negative

Step 1; Write the formula for calculating change in energy

$\Delta E\text{ }=\text{ q }+\text{ w}$

Since heat is released to the surrounding, then q = -12J

Recall, that work done by the system on the surroundings is always negative

Hence, w = -4.2J

Step 2; Substitute the given data into the formula in step 1

$\begin{gathered} \text{ }\Delta E\text{ = q + w} \\ \text{ }\Delta E\text{ }=\text{ -12.4 }+\text{ \lparen-4.2\rparen} \\ \text{ }\Delta E\text{ = -12.4 - 4.2} \\ \text{ }\Delta E\text{ }=\text{ -16.6J} \end{gathered}$

Therefore, the change i

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1 year ago

A sample of a compound contains 32.0 g C and 8.0 g H. Its molar mass is 30.0 g/mol. What is the compound’s molecular formula

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The compound's molecular formula is C2H6. This is obtained by:

mass moles divided by smallest moles
C 32g 32/12 = 2.67 1
H 8g 8/1.01 = 7.92 approx. 3

Next, divide both terms by the smallest number of moles, 2.67. This gives 1 and 3. So the empirical formula is CH3 which has a molar mass of 15g/mol. Given the molar mass of the molecular formula as 30g/mole, we can calculate the factor by which to multiply the subscripts of CH3.

X = molar mass of molecular formula / molar mass of empirical formula = 30/15
X=2

So (CH3)2 is C2H6.

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2 years ago

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stira [4]

Answer:

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Explanation:

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4 Fe + 3 O₂ → 2 Fe₂O₃

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Fe: 4 moles
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You can apply the following rule of three: if by stoichiometry 4 moles of Fe produce 2 moles of Fe₂O₃, 0.15 moles of Fe produce how many moles of Fe₂O₃?

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moles of Fe₂O₃= 0.075

<u><em>0.075 moles of iron oxide would be produced by complete reaction of 0.15 moles of iron.</em></u>

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