All categories

2 years ago

According to the following thermochemical equation, what mass of H2O (in g) must form in order to produce 488 kJ of energy?

Chemistry

1 answer:

vladimir1956 [14]2 years ago

7 0

Answer:

m = 95.47 g

Explanation:

The reaction is missing. I found it, and here's the missing part:

SiO2(s) + 4HF(s) -> SiF4(s) + 2H2O(l) ΔH°rxn = -184 kJ

According to the reaction, 2 moles of water are produced in this reaction, and this also produces 488 kJ of energy.

To calculate the mass of any compound we use the expression:

m = n*MM

The molar mass of water is 18 g/mol. so, we need the moles of water to get the mass. The relation between the heat and energy is the following:

ΔH = Q/n ---> solving for n:

n = Q/ΔH.

So, let's calculate moles of water used here:

n = 488 * 2/184

n = 5.304 moles

Now we can calculate the mass:

m = 5.304 * 18

m = 95.47 g

You might be interested in

balance the following reaction using LCM method by showing each steps Pb (N3)2 + Cr(MnO4)2  Cr2O3 + MnO2 + Pb3O4+ NO

blsea [12.9K]

here's the answer to your question

5 0

1 year ago

(f) what is the observed rotation of 100 ml of a solution that contains 0.01 mole of d and 0.005 mole of l? (assume a 1-dm path

never [62]

Answer: .01 moles of D to .005 moles of L ~ so, .01+.005 = .015 total; using this total value, divide the portions of D and L. so .01/.015 to .005/.015 ~ 67% D to 33% L. And thus, the enantiomer excess will be 34%.

4 0

2 years ago

Read 2 more answers

The human body is 0.0040% iron. How many milligrams of iron does a 165 pound person contain?

Fofino [41]

Answer:

in a body of 165 pounds, the iron content is 2993.707 mg

Explanation:

% iron = 0.0040% = (mass iron / mass human) * 100

⇒ mass iron / mass human = 4 E-5

∴ mass human = 165 pounds

⇒ mass iron = 165 pounds * 4 E-5

⇒ mass iron = 6.6 E-3 pounds * ( 453.592 g/pound ) * ( 1000 mg/g )

⇒ mass iron = 2993.707 mg iron

8 0

2 years ago

What mass of methanol is combusted in a reaction that produces 112 L of Co2 at STP?

AlekseyPX

Answer

D 160g

Explanation:

Write the equation:

Combustion reactions use oxygen and release water and heat, so

CH₃OH(g) + O₂(g) → CO₂(g) + H₂O(g)

Balance that:

2CH₃OH(g) + 3O₂(g) → 2CO₂(g) + 4H₂O(g)

Find moles of carbon dioxide:

We need to know the number of moles of CO₂. This rxn is at STP, so at STP one mole of gas = 22.4 liters.

112 L * 1 mol/22.4 L = 5 mol CO₂

Find moles of methanol:

Based on the chemical equation, for every 2 mol methanol, there are 2 mol carbon dioxide. So for every 5 mol carbon dioxide, there are 5 mol methanol!

5 mol CO₂ = 5 mol CH₃OH

Molar mass of methanol: 12.01 + 3*1.008 + 16.00 + 1.008 = 32.04 g/mol

Moles of methanol: 5 mol * 32.04 g/mol = 160.2 g methanol

≈ 160 mol methanol

8 0

2 years ago

The standard free energy ( Δ G ∘ ′ ) (ΔG∘′) of the creatine kinase reaction is − 12.6 kJ ⋅ mol − 1 . −12.6 kJ⋅mol−1. The Δ G ΔG

Dmitrij [34]

Answer:

The concentration of [ADP] = 21.896*10^-6 μM

Explanation:

Given Data:

creatine + ATP -----------> ADP + creatine phosphate

ΔG∘ = -12.6 KJ/mole = -12600 J/mole

ΔG = -0.1 KJ/mole = -100 J/mole

[Creatine phosphate] = 25 mM = 25*10^-3 M

[Creatine] = 17 mM = 17*10^-3 M

[ATP] =5mM = 5*10^-3M

Calculating the concentration of [ADP] using the formula;

ΔG = ΔG∘ + RTlnQc

Substituting, we have

-12600 = -100 + 8.314*298lnQc

-12600+100 = 8.314*298lnQc

-12500 = 2477.57lnQc

lnQc = -12500/2477.57

lnQc = -5.045

Qc = e^ -5.045

Qc = 6.44*10^-3

But,

Qc = [Creatine phosphate]*[ADP]/[creatine]*[ATP]

6.44*10^-3 = 25*10^-3*[ADP]/ (17*10^-3* 5*10^-3)

6.44*10^-3 = 25*10^-3[ADP]/8.5*10^-5

6.44*10^-3 * 8.5*10^-5 = 25*10^-3[ADP]

5.474*10^-7 = 25*10^-3[ADP]

[ADP] = 5.474*10^-7 /25*10^-3

= 2.1896 *10^-5 M

= 21.896*10^-6 μM

Therefore, the concentration of [ADP] = 21.896*10^-6 μM

3 0

2 years ago