CHEMISTRY HIGH SCHOOL

Calculate the change of enthalpy for the reaction CH4 (g) + NH3 (g) --> HCN (g) +3H2 (g) from the following reactions: Reaction 1: N2 (g) + 3H2 (g) --> 2NH3 (g) Change in enthalpy: -91.8 kJ/mol

Reaction 2: C (s, graphite) + 2H2 (g) --> CH4 (g) Change in enthalply: -74.9 kJ/mol

Reaction 3: H2 (g) + 2C (s, graphite) + N2 (g) --> 2HCN (g) Change in enthalpy: +270.3 kJ/mol

Include the following:

The numerical answer with correct units.
State which reactions, if any, you had to "Flip".
State which reactions you had to multiply, if any, to get the correct amount of the compound.

Answers

Answer 1

Answer:

The enthalpy for the reaction, ΔH rxn is 255.95 kJ/mol

From the question,

We are to calculate the change in enthalpy for the reaction

CH₄(g) + NH₃(g) → HCN(g) +3H₂(g)

From the given reactions

Reaction 1: N₂(g) + 3H₂(g) → 2NH₃(g) Change in enthalpy: -91.8 kJ/mol

Reaction 2: C(s, graphite) + 2H₂(g) → CH₄(g) Change in enthalply: -74.9 kJ/mol

Reaction 3: H₂(g) +2C(s, graphite) +N₂(g) → 2HCN (g) Change in enthalpy: +270.3 kJ/mol

First, flip reactions 1 and 2 to get reaction 4 and 5 respectively

Reaction 4: 2NH₃(g) → N₂(g) + 3H₂(g) ΔHo : 91.8 kJ/mol

Reaction 5: CH₄(g) → C(s, graphite) + 2H₂(g) ΔHo : 74.9 kJ/mol

Now, multiply reactions 4 and 3 by half (1/2) to get 6 and 7 respectively

Reaction 6: NH₃(g) → ¹/₂N₂(g) + ³/₂H₂(g) ΔHo : 45.9 kJ/mol

Reaction 7: ¹/₂H₂(g) +C(s, graphite) +¹/₂N₂(g) → HCN (g) ΔHo : +135.15 kJ/mol

Now,

Add reactions 5, 6, and 7 together

Reaction 5: CH₄(g) → C(s, graphite) + 2H₂(g) ΔHo : 74.9 kJ/mol

Reaction 6: NH₃(g) → ¹/₂N₂(g) + ³/₂H₂(g) ΔHo : 45.9 kJ/mol

Reaction 7: ¹/₂H₂(g) +C(s, graphite) +¹/₂N₂(g) → HCN(g) ΔHo : +135.15 kJ/mol

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CH₄(g) + NH₃(g) → HCN(g) + 3H₂(g) ΔH rxn = 255.95 kJ/mol

Hence, the enthalpy for the reaction, ΔH rxn is 255.95 kJ/mol

Learn more here: brainly.com/question/13779366

Answer 2

Answer:

Answer:

255.8 kj/mol

Explanation:

So this is a Hess' Law problem, the CH₄ (g) + NH₃ (g) --> HCN (g) + 3H₂ (g) is what we want the other reactions to reflect. I usually set up problems like these like this in order to determine which reaction needs a coefficient change:

N₂ + 3H₂ --> 2NH₃ (ΔH=-91.8)

C + 2H₂ --> CH₄ (ΔH=-74.9

H₂ + 2C + N₂ --> 2HCN (ΔH=270.3)

CH₄ + NH₃ --> HCN + 3H₂

(I left out the states because it'll make the math easier) So, we want things to cancel out, meaning some of the reactants and products need to change places in order to do so. For the first reaction, we'd want to multiply the coefficients by $(1)/(2)$ in order to have it cancel out with the other reactions. For the third reaction, we'd want to we'd want to switch the products/reactants and multiply the coefficients by $(1)/(2)$ . Keep in mind whatever we do to the equation, we do to the ΔH. Should look like:

$(1)/(2)$ N₂ + $(3)/(2)$ H₂ --> NH₃ (ΔH=-45.9)

C + 2H₂ --> CH₄ (ΔH=-74.9)

HCN --> $(1)/(2)$ H₂ + C + $(1)/(2)$ N₂ (ΔH=-135)

CH₄ + NH₃ --> HCN + 3H₂

Everything cancels, so that means we can add all the ΔH, which should be -255.8 kj/mol, but we also change the sign in order to reflect what's happening in the reaction. (Sorry this is so long)

Physical change.

Explanation:

This is a physical change.

The reason for escaping pops is the water caught internal parts it's bit.
Inside the event that the bit is warmed to a tall satisfactory temperature, this water will modify into steam. Due to the troublesome and for the preeminent parcel nonporous shell, the steam has no put to go, coming nearly in a buildup of weight internal parts the bit.
Once the weight gets tall satisfactory and the temperature comes to around 180 degrees Celsius (355 degrees Fahrenheit), the pops escape from the skillet or bursts and the popcorn is turned internal parts out.

How many moles of water, H2O, contain 2.0×1022 molecules of water? (See the hints for assistance in interpreting scientific notation.)Express the quantity in moles to two significant figures.

Answers

In this question, what are we really being asked? We are being asked about the number of moles there in 2.0x10^22 molecules of H2O.

We are going to use the formula,
Number of moles = Number of molecules / Avogadro's number

We have the number of molecules: 2.0 x 10^22
Avogadro's number: 6.02 x 10^23

Now we will plug in our information in a scientific calculator:

(2.0 x 10^22) / (6.02 x 10^23) = 0.03 moles is our answer.

Solutions of aluminum nitrate and sodium sulfate react to form sodium nitrate and aluminum sulfate. Classify this reaction.2Al(NO3)3(aq) + 3Na2SO4(aq) → Al2(SO4)3(s) + 6NaNO3(aq)
A) Synthesis
B) Decomposition
C) Double Replacement
D) Single Replacement
I choose C was wondering if I was correct

Answers

C is the correct answer. Double displacement reaction, also called as metathesis, is a type of reaction wherein two compounds react to form new compounds. This case the cations and the anions of the reactants replace each other forming the new compounds.

Answer:

C: Double Replacement

Explanation:

Elements abundant in the body are not abundant on Earth.
a. True
b. False

Answers

Answer:

false is the correct answer,

Explanation:

The most abundant elements present in the body is carbon, oxygen, hydrogen, calcium, nitrogen, and phosphorus.

About 99 percent of the human body is made of ( carbon, hydrogen,oxygen, calcium, nitrogen, and phosphorus.) elements and 0.85 percent is made up of sulfur, sodium, potassium, chlorine, and magnesium and these all elements are abundant on Earth.

Thus the Elements abundant in the body are abundant on Earth.

B. False

Most of the body is made up of oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus, all of which are abundant on Earth.

Your tongue and nose work separately.
True
False