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2 years ago

Under what conditions is the change in internal energy, δe rxn , equal to the heat evolved in a chemical reaction?

1 answer:

4 0

the first law says that the change in internal energy of a system is given by:

δE = δq + δw

where δE is the i change in internal energy, 

δq is the amount of thermal energy added to the system from the surroundings 

δw is the l work done *on* the system *by* the surroundings. 

For a system only undergoing expansion work,
δw = -pδV, so: 

δE = δq - p δV 
when δV = 0, then δe=δq

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In a 74.0-g aqueous solution of methanol, CH4O, the mole fraction of methanol is 0.140. What is the mass of each component?

Salsk061 [2.6K]

Answer:

The correct answer is 16.61 grams methanol and 57.38 grams water.

Explanation:

The mole fraction (X) of methanol can be determined by using the formula,

X₁ = mole number of methanol (n₁) / Total mole number (n₁ + n₂)

X₁ = n₁/n₁ + n₂ = 0.14

n₁ / n₁ + n₂ = 0.14 ---------(i)

n₁ mole CH₃OH = n₁ mol × 32.042 gram/mol (The molecular mass of CH₃OH is 32.042 grams per mole)

n₁ mole CH₃OH = 32.042 n₁ g

n₂ mole H2O = n₂ mole × 18.015 g/mol

n₂ mole H2O = 18.015 n₂ g

Thus, total mole number is,

32.042 n₁ + 18.015 n₂ = 74 ------------(ii)

From equation (i)

n₁/n₁ + n₂ = 0.14

n₁ = 0.14 n₁ + 0.14 n₂

n₁ - 0.14 n₁ = 0.14 n₂

n₁ = 0.14 n₂ / 1-0.14

n₁ = 0.14 n₂/0.86 ----------(iii)

From eq (ii) and (iii) we get,

32.042 × 0.14/0.86 n₂ + 18.015 n₂ = 74

n₂ (32.042 × 0.14/0.86 + 18.015) = 74

n₂ = 74 / (32.042 × 0.14/0.86 + 18.0.15)

n₂ = 3.1854 mol

From equation (iii),

n₁ = 0.14/0.86 n₂

n₁ = 0.14/0.86 × 3.1854

n₁ = 0.5185 mol

Now, presence of water in the mixture is,

= 3.1854 mole × 18.015 gram per mole

= 57.38 grams

Methanol present in the mixture is,

= 0.5185 mol × 32.042 gram per mole

= 16.61 grams

8 0

3 years ago

What can you tell about the people that supported Hitler and his party??

Greeley [361]

Answer:

Well, that was just me........................

7 0

3 years ago

Which of the following does not happen during a chemical change?

Maurinko [17]

It's C. Compounds are broken down.

3 0

2 years ago

A sealed container can hold

svp [43]

0.216 moles of gas can the container hold if a sealed container can hold 0.325 L of gas at 1.00 atm and 293 K.

<h3>What is an ideal gas equation?</h3>

The ideal gas law (PV = nRT) relates the macroscopic properties of ideal gases. An ideal gas is a gas in which the particles (a) do not attract or repel one another and (b) take up no space (have no volume).

PV=nRT, where n is the moles and R is the gas constant. Then divide the given mass by the number of moles to get molar mass.

Given data:

R = gas constant = 0.08206 L.atm / mol K

T = temperature, Kelvin

V=5 L

P = 1.05 atm

T = 296 K

Putting value in the given equation:

$\frac{PV}{RT}=n$

$n= \frac{1.05 atm\; X \;5 L}{ 0.08206 L.atm / mol K X 296 K}$

Moles = 0.216 moles

Hence, 0.216 moles of gas can the container hold if a sealed container can hold 0.325 L of gas at 1.00 atm and 293 K.

Learn more about the ideal gas here:

brainly.com/question/27691721

#SPJ1

6 0

2 years ago

BRAINLIESTT ASAP!! PLEASE HELP ME :)

AURORKA [14]

Answer:

Here's what I get.

Explanation:

Mg + 2HCl ⟶ MgCl₂ + H₂

According to the Law of Conservation of Mass, the total mass of the products must equal the total mass of the reactants.

However, one of the products is a gas, hydrogen. The gas escapes into the atmosphere, so you will not be weighing it at the end of the reaction.

The mass of the test tube and contents after the reaction will be less than before the reaction.

However, that doesn't violate the Law of Conservation of Mass. You just didn't measure the mass of all the products.

8 0

3 years ago