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3 years ago

Given the equation:

Chemistry

1 answer:

svetoff [14.1K]3 years ago

7 0

Answer:

4 moles of HCl will be required to produce 2 moles of H2.

Explanation:

A balanced chemical equation gives the stoichiometric ration of moles of reactants required to produce a certain number of moles of products. The ratio of moles of reactants to moles of products is known as the mole ratio and is constant for a given chemical reaction.

In the given balanced equation of reaction shown below:

Zn + 2HCl → ZnCl2 + H2

The mole ratio of HCl and H2 is 2:1. This means that in this reaction between Zinc metal and hydrochoric acid to produc zinc chloride and hydrogen gas, every two moles of hydrochloric acid used in the reaction will result in the production of one mole of hydrogen gas.

Therefore for two moles of H2 to be obtained from the reaction, twice the number of moles of HCl is required.

Moles of HCl required = 2 × 2 moles = 4 moles of HCl.

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Which is the correct Lewis dot structure of NH2-?

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D. The total number of valence electrons is 8 and D represents that. D also correctly uses the octet rule for N and duet rule for H.

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3 years ago

Read 2 more answers

Pentaborane-9, B5H9, is a colorless, highly reactive liquid that will burst into flame when exposed to oxygen. The reaction is 2

mina [271]

<u>Answer:</u> The amount of energy released per gram of $B_5H_9$ is -71.92 kJ

<u>Explanation:</u>

For the given chemical reaction:

$2B_5H_9(l)+12O_2(g)\rightarrow 5B_2O_3(s)+9H_2O(l)$

The equation used to calculate enthalpy change is of a reaction is:

$\Delta H^o_{rxn}=\sum [n\times \Delta H^o_f_{(product)}]-\sum [n\times \Delta H^o_f_{(reactant)}]$

The equation for the enthalpy change of the above reaction is:

$\Delta H^o_{rxn}=[(5\times \Delta H^o_f_{(B_2O_3(s))})+(9\times \Delta H^o_f_{(H_2O(l))})]-[(2\times \Delta H^o_f_{(B_5H_9(l))})+(12\times \Delta H^o_f_{(O_2(g))})]$

Taking the standard enthalpy of formation:

$\Delta H^o_f_{(B_2O_3(s))}=-1271.94kJ/mol\\\Delta H^o_f_{(H_2O(l))}=-285.83kJ/mol\\\Delta H^o_f_{(B_5H_9(l))}=73.2kJ/mol\\\Delta H^o_f_{(O_2(g))}=0kJ/mol$

Putting values in above equation, we get:

$\Delta H^o_{rxn}=[(5\times (1271.94))+(9\times (-285.83))]-[(2\times (73.2))+(12\times (0))]\\\\\Delta H^o_{rxn}=-9078.57kJ$

We know that:

Molar mass of pentaborane -9 = 63.12 g/mol

By Stoichiometry of the reaction:

If 2 moles of $B_5H_9$ produces -9078.57 kJ of energy.

Or,

If $(2\times 63.12)g$ of $B_5H_9$ produces -9078.57 kJ of energy

Then, 1 gram of $B_5H_9$ will produce = $\frac{-9078.57kJ}{(2\times 63.12)}\times 1g=-71.92kJ$ of energy.

Hence, the amount of energy released per gram of $B_5H_9$ is -71.92 kJ

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3 years ago

Carbonate oxidation number

Svetllana [295]

Answer:

-2

Explanation:

carbonate oxifation number is -2

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3 years ago

A system fitted with a piston expands when it absorbs 53.1 ) of heat from the surroundings. The piston is working against a pres

Hoochie [10]

Answer:

d. 60.8 L

Explanation:

Step 1: Given data

Heat absorbed (Q): 53.1 J

External pressure (P): 0.677 atm

Final volume (V2): 63.2 L

Change in the internal energy (ΔU): -108.3 J

Step 2: Calculate the work (W) done by the system

We will use the following expression.

ΔU = Q + W

W = ΔU - Q

W = -108.3 J - 53.1 J = -161.4 J

Step 3: Convert W to atm.L

We will use the conversion factor 1 atm.L = 101.325 J.

-161.4 J × 1 atm.L/101.325 J = -1.593 atm.L

Step 4: Calculate the initial volume

First, we will use the following expression.

W = - P × ΔV

ΔV = - W / P

ΔV = - 1.593 atm.L / 0.677 atm = 2.35 L

The initial volume is:

V2 = V1 + ΔV

V1 = V2 - ΔV

V1 = 63.2 L - 2.35 L = 60.8 L

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3 years ago

Calculate the number of molecules in 100. g of O2 *

Sindrei [870]

I am pretty sure the answer is 6.25 molecules
See picture for explanation

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3 years ago