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2 years ago

If the heat of combustion of hydrogen is -285.8KJ,what is the heat of formation of water

Chemistry

1 answer:

ExtremeBDS [4]2 years ago

5 0

Answer:

The heat of formation of H2O(g) is likely to be-242,8KJ.

Explanation:

The heat of formation of H2O(g) will be slightly lower than the heat of formation of H2O(1)as some energy is released during condensation of water vapour to liquid water.

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Two gases, A and B, are at equilibrium in a sealed cylinder. Individually, gas A is colorless, while gas B is dark colored. The

Dmitriy789 [7]

Answer:

(a) color

(b) endothermic

(c)

b The ΔH value would have the same magnitude value but opposite sign.

c The K expression would be inverted.

Explanation:

Let's consider the following reaction at equilibrium.

A(g) ⇄ 2 B(g)

colorless dark colored

(a) The cylinder should appear (color or colorless)

At equilibrium, there is a mixture of A and B, so the cylinder should appear colored.

(b) When the system is cooled, the cylinder's appearance becomes very light colored. Therefore, the reaction must be (endothermic or exothermic)

According to Le Chatelier's Principle when a perturbation is made to a system at equilibrium it will react to counteract such effect. When the system is cooled, it will tend to increase the temperature by releasing heat. In this case, the reaction is endothermic so when the reverse reaction is favored, colorless A is favored as well.

Suppose the reaction equation were written as follows: 2 B(g) ⇄ A(g)

(c) Which of these statements would then be true?

a The value of K would not change. FALSE. The new K would be the inverse of the direct K.

b The ΔH value would have the same magnitude value but opposite sign. TRUE. This is stated by Lavoisier-Laplace Law.

c The K expression would be inverted. TRUE. What was product before now is reactant and vice-versa.

d The color of the cylinder would be darker. FALSE. Changing the way the reaction is expressed has no effect on the equilibrium.

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Explanation:

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2 years ago

A solution is prepared by dissolving 42.0 g of glycerin, C3H8O3, in 186 g of water with a final volume of 200.0 mL. a. Calculate

trapecia [35]

Answer:

For a: The molality and molarity of the given solution is 2.45m and 2.28 M respectively.

For b: The molarity of the solution when more water is added is 0.912 M

Explanation:

For a:

To calculate the molality of solution, we use the equation:

$Molarity=\frac{m_{solute}\times 1000}{M_{solute}\times W_{solvent}\text{ in grams}}$

Where,

$m_{solute}$ = Given mass of solute $(C_3H_8O_3)$ = 42.0 g

$M_{solute}$ = Molar mass of solute $(C_3H_8O_3)$ = 92.093 g/mol

$W_{solvent}$ = Mass of solvent (water) = 186 g

Putting values in above equation, we get:

$\text{Molality of }C_3H_8O_3=\frac{42\times 1000}{92.093\times 186}\\\\\text{Molality of }C_3H_8O_3=2.45m$

To calculate the molarity of solution, we use the equation:

$\text{Molarity of the solution}=\frac{\text{Mass of solute}\times 1000}{\text{Molar mass of solute}\times \text{Volume of solution (in mL)}}$ .....(1)

We are given:

Molarity of solution = ?

Molar mass of $(C_3H_8O_3)$ = 92.093 g/mol

Volume of solution = 200 mL

Mass of $(C_3H_8O_3)$ = 42 g

Putting values in above equation, we get:

$\text{Molality of }C_3H_8O_3=\frac{42\times 1000}{92.093\times 200}\\\\\text{Molality of }C_3H_8O_3=2.28M$

Hence, the molality and molarity of the given solution is 2.45m and 2.28 M respectively.

For b:

Now, the 300 mL water is added to the solution. So, the total volume of the solution becomes (200 + 300) = 500 mL

Using equation 1 to calculate the molarity of solution, we get:

Molar mass of $(C_3H_8O_3)$ = 92.093 g/mol

Volume of solution = 500 mL

Mass of $(C_3H_8O_3)$ = 42 g

Putting values in equation 1, we get:

$\text{Molality of }C_3H_8O_3=\frac{42\times 1000}{92.093\times 500}\\\\\text{Molality of }C_3H_8O_3=0.912M$

Hence, the molarity of the solution when more water is added is 0.912 M

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3 years ago

If the heat of combustion of hydrogen is -285.8KJ,what is the heat of formation of water​

If the heat of combustion of hydrogen is -285.8KJ,what is the heat of formation of water