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1 year ago

1. A chemist prepares hydrogen fluoride by means of the following reaction:

Chemistry

1 answer:

Natasha_Volkova [10]1 year ago

8 0

Answer:

a) Theoretical Yield of HF = 5.64 grams

b) Percentage Yield = 39%

Explanation:

Reaction Given:

CaF2 + H2SO4 -> CaSO4 + 2HF

CaF2 = 11g

H2SO4 = Used in excess

HF = 2.2 g production = Actual Yield

So, Let's write down the molar masses:

Molar Mass of CaF2 = 78 g /mol

Molar Mass of HF = 20 g/mol

From the reaction, we can see the 1 mole of CaF2 gives the 2 moles of HF

i.e

a) Theoretical Yield of HF:

1 mole CaF2 = 2 moles HF

78 g CaF2 = 2 x 20 g of HF

78 g CaF2 = 40 g of HF

1 g CaF2 = 40g/78g of HF

And in the question it is given that chemist used 11 g of CaF2 so,

1 x 11 g of CaF2 = 11 x 40/78 g of HF

11 g of CaF2 = 440/78 g of HF

11 g of CaF2 = 5.64 g of HF

And this is the theoretical yield

Theoretical Yield of HF = 5.64 grams

b) Now, calculate the Percentage Yield of HF

Percentage Yield = Actual Yield /Theoretical Yield x 100

Percentage Yield = 2.2 g /5.64 g x 100

Percentage Yield = 39%

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When CO2(g) reacts with H2(g) to form C2H2(g) and H2O(g), 23.3 kJ of energy are absorbed for each mole of CO2(g) that reacts. Wr

kupik [55]

Answer:

$2CO_{2}(g)+5H_{2}(g)\rightarrow C_{2}H_{2}(g)+4H_{2}O(g)-46.6kJ$

Explanation:

As energy is absorbed therefore it is an endothermic reaction. Hence energy value should be written in the product side with a negative sign.

Reaction: $CO_{2}(g)+H_{2}(g)\rightarrow C_{2}H_{2}(g)+H_{2}O(g)$

C balance: $2CO_{2}(g)+H_{2}(g)\rightarrow C_{2}H_{2}(g)+H_{2}O(g)$

H and O balance: $2CO_{2}(g)+5H_{2}(g)\rightarrow C_{2}H_{2}(g)+4H_{2}O(g)$

Here 2 moles of $CO_{2}$ react. So, energy absorbed during the reaction is $(2\times 23.3)$ kJ or 46.6 kJ

Energy balance: $2CO_{2}(g)+5H_{2}(g)\rightarrow C_{2}H_{2}(g)+4H_{2}O(g)-46.6kJ$

Balanced thermochemical equation:

$2CO_{2}(g)+5H_{2}(g)\rightarrow C_{2}H_{2}(g)+4H_{2}O(g)-46.6kJ$

3 0

1 year ago

If the value of Kc for the reaction is 2.50, what are the equilibrium concentrations if the reaction mixture was initially 0.500

ratelena [41]

Answer: The equilibrium concentration of sulfur dioxide, nitrogen dioxide, sulfur trioxide, nitrogen monoxide is 0.196 M, 0.196 M, 0.309 M and 0.309 M respectively.

Explanation:

We are given:

Initial concentration of sulfur dioxide = 0.500 M

Initial concentration of nitrogen dioxide = 0.500 M

Initial concentration of sulfur trioxide = 0.00500 M

Initial concentration of nitrogen monoxide = 0.00500 M

The chemical reaction follows:

$SO_2+NO_2\rightleftharpoons SO_3+NO$

Initial: 0.500 0.500 0.005 0.005

At eqllm: 0.500-x 0.500-x 0.005+x 0.005+x

The expression of equilibrium constant for the above reaction follows:

$K_c=\frac{[SO_3][NO]}{[SO_2][NO_2]}$

We are given:

$K_c=2.50$

Putting values in above equation, we get:

$2.50=\frac{(0.005+x)\times (0.005+x)}{(0.500-x)\times (0.500-x)}\\\\x=0.304,1.37$

Neglecting the value of x = 1.37, because change cannot be greater than the initial concentration

So, equilibrium concentration of sulfur dioxide = $(0.500-x)=(0.500-0.304)=0.196M$

Equilibrium concentration of nitrogen dioxide = $(0.500-x)=(0.500-0.304)=0.196M$

Equilibrium concentration of sulfur trioxide = $(0.00500+x)=(0.00500+0.304)=0.309M$

Equilibrium concentration of nitrogen monoxide = $(0.00500+x)=(0.00500+0.304)=0.309M$

Hence, the equilibrium concentration of sulfur dioxide, nitrogen dioxide, sulfur trioxide, nitrogen monoxide is 0.196 M, 0.196 M, 0.309 M and 0.309 M respectively.

4 0

2 years ago

If you have 2.41 × 1024 atoms of copper, how many moles of copper do you have? If you have 2.41 atoms of copper, how many moles

Bogdan [553]

Answer:

4.00 moles

Explanation:

Avogadro´s number is 6.022 x 10²³ molecules, atoms, particles, etc.

Here we are talking of atoms of copper, so 1 mol of copper is equal to 6.022 x 10²³ atoms, and we only need to setup the proportion to find the number of mol in 2.41 x 10²⁴ atoms. ( Think of it like a dozen, avogadro´s is 6.022 x 10²³ )

( 1 mol copper/ 6.022 x 10²³ atoms of copper ) x 2.41 x 10²⁴ atoms

= 4.00 moles

4 0

2 years ago

One of the buffers that contribute to pH stability in human blood is carbonic acid (H2CO3). Carbonic acid is a weak acid that, w

bonufazy [111]

Answer: the HCO3- to act as a base and remove excess H by the formation of H2CO3

Explanation:

H2CO3 in an aqueous solution is a buffer. This means the reaction is the following:

H2CO3 ------ HCO3- + H+

Then, the HCO3- that was formed acts as a base (absorbing a proton) like this

HCO3- + H+ ------- H2CO3

If there was an increase in H+, there would be an increase in the second reaction in an effort to neutralize that acid, thus making the H2CO3 more concentrated

7 0

2 years ago

Calculate the pressure exerted by 66.0 g of CO2 gas at -14.5°C that occupies a volume of 50.0 L

Anestetic [448]

Answer:

Pressure = 0.64 atm

Explanation:

Use Ideal Gas Law PV = nRT => P = nRT/V

n = moles CO₂(g) = 66g/44g/mol = 1.5 mol CO₂

R = Gas Constant = 0.08206 L·atm/mol·K

T = Temperature = -14.5°C = (-14.5 + 273)K = 258.5 K

V = 50.0 Liters

P = (1.5 mol)(0.08206 L·atm/mol·K)(258.5 K)/(50.0 L) = 0.64 atm

5 0

2 years ago