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4 years ago

13

Use the standard reaction enthalpies given below to determine ΔH°rxn for the following reaction: P4(g) + 10 Cl2(g) → 4PCl5(s) ΔH

°rxn = ? Given: PCl5(s) → PCl3(g) + Cl2(g) ΔH°rxn= +157 kJ P4(g) + 6 Cl2(g) → 4 PCl3(g) ΔH°rxn = -1207 kJ

1 answer:

Pie4 years ago

3 0

Answer: -1835 kJ

Explanation:

According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.

According to Hess’s law, the chemical equation can be treated as algebraic expressions and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.

$PCl_5(s)\rightarrow PCl_3(g)+Cl_2(g)$ $\Delta H_1=+157kJ$ (1)

$P_4(g)+6Cl_2\rightarrow 4PCl_3(g)$ $\Delta H_2=-1207J$ (2)

Net chemical equation:

$P_4(g)+10Cl_2(g)\rightarrow 4PCl_5(s)$ $\Delta H=?$ (3)

Multiplying equation (1) by 4, and reversing we get

$4PCl_3(g)+4Cl_2(g)\rightarrow 4PCl_5(s)$ $\Delta H_4=4\times -157kJ=-628kJ$ (4)

Adding (2) and (4)

$P_4(g)+10Cl_2(g)\rightarrow 4PCl_5(s)$ $\Delta H_3=\Delta H_2+\Delta H_4=-1207kJ-628kJ=-1835kJ$

Thus enthaply change for the reaction is -1835 kJ.

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17) Chlorine and Fluorine react to form gaseous chlorine trifluoride. You start with 1.75 mole of chlorine and 3.68 moles of flu

Mama L [17]

Answer:

a) $Cl_2 + 3F_2 \rightarrow 2ClF_3$

b) $F_2$ is the limiting reagent

c) Moles of $ClF_3$ produced = 2.45 mol

b) Moles of $Cl_2$ left = 1.75 -1.22 = 0.53

Explanation:

a) Balanced reaction:

$Cl_2 + 3F_2 \rightarrow 2ClF_3$

b)

No. of mole of $Cl_2 = 1.75\ mol$

No. of mole of $F_2 = 3.68\ mol$

$Cl_2 + 3F_2 \rightarrow 2ClF_3$

As, it is clear from the reaction that,

1 mol of $Cl_2$ requires 3 moles of $F_2$

1.75 mol of $Cl_2$ require = 1.75 × 3 = 5.25 mol of $F_2$

As, only 3.68 mol of $F_2$ is present, so $F_2$ is the limiting reagent.

c)

3 moles of $F_2$ form 2 moles of $ClF_3$

3.68 moles of $F_2$ will form = $\frac{2}{3} \times 3.68 = 2.45\ mol\ of\ ClF_3$

d)

$Cl_2$ is present in excess.

3 moles of $F_2$ requires 1 mol of $Cl_2$

3.68 moles of $F_2$ will require = $\frac{1}{3} \times 3.68 = 1.22\ mol\ of\ Cl_2$

$Cl_2$ left = 1.75 -1.22 = 0.53 mol

6 0

4 years ago

Read 2 more answers

A certain reaction at equilibrium has more moles of gaseous products than of gaseous reactants.(b) Write a statement about the r

mojhsa [17]

To be equal as $K_p$ , $K_c$ needs to be divided by $(RT)^{\Delta n}$

<h3>Briefly explained</h3>

When the amount of gaseous reactant is greater than the amount of gaseous product, where $n_{products} < n_{reactants}$ ,

then = $K_p < K_c$

It's because $\Delta n$ is negative, which places (RT) in the denominator. This is how the equation will now appear.

$K_p = K_c(RT)^{-\Delta n} = \frac{ K_c}{(RT)^{\Delta n}}$

Here you can observe the value of $K_c$ is greater than $K_p$ . To be equal as $K_p$ , $K_c$ needs to be divided by $(RT)^{\Delta n}$

<h3>What is Δngas?</h3>

The number of moles of gas that move from the reactant side to the product side is denoted by the symbol ∆n or delta n in this equation.

Once more, n represents the growth in the number of gaseous molecules the equilibrium equation can represent. When there are exactly the same number of gaseous molecules in the system, n = 0, Kp = Kc, and both equilibrium constants are dimensionless.

<h3>Definition of equilibrium</h3>

When a chemical reaction does not completely transform all reactants into products, equilibrium occurs. Many chemical processes eventually reach a state of balance or dynamic equilibrium where both reactants and products are present.

Learn more about equilibrium

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6 0

2 years ago

What are two properties of liquids, solids, gases and matter. What are two important things about them.

larisa86 [58]

Solids— have tightly packed molecules, structured shape

Liquid— have no definite shape and the molecules are not tightly packed like a solid, they are a lot more loose.

Gas— No structure at all, molecules are free flowing

Sorry I couldn’t be a better help.. but I hope this gives you a bit of an idea :)

4 0

4 years ago

a minute sample of AlCl3 is analyzed for chlorine.The analysis reveal that there are 12 chloride ions present in the sample. How

nekit [7.7K]

You can solve this by saying that there are 3 Cl for every 1 Al therefore a ratio of 1:3. If you have 12 Cl ions you can find how many Al ions there is
so (x)Al : 12 a unkown amount of Al ions gives you 12 Al ions from the ratio we know that we have 1 Al for 3 Cl therefore we can divide 12 by 3 to get the number of Al ions. The answer is 4 Al ions for 12 Cl ions.
Hope this helps :).

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3 years ago

25cc of 5 % NaOH solution neutralized 30cc of h2sO4 solution. Whatis normality of H2SO4?

MAVERICK [17]

The normality of the H₂SO₄ that reacted with 25cc of 5 % NaOH solution is 1.1 N.

<h3>What is the molarity of 5% NaOH?</h3>

The molarity of 5% NaOH is 1.32 M

25 cc of NaOH neutralized 30cc of H₂SO₄ solution.

Equation of reaction is given below:

2 NaOH + H₂SO₄ ---> Na₂SO₄ + 2 H₂O

Molarity of H₂SO₄ = 1.32 x 1 x 25/(30 x 2) = 0.55 M

Normality = Molarity × moles of H⁺ ions per mole of acid

moles of H⁺ ions per mole of H₂SO₄ = 2

Normality of H₂SO₄ = 0.55 x 2 = 1.1 N

In conclusion, the normality of an acid is determined from the molarity and the moles of H⁺ ions per mole of acid.

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7 0

2 years ago