Which is larger? C atom or F atom? Explain why.

Calculate the equilibrium concentration of H 3 O H3O in a 0.20 M M solution of oxalic acid. Express your answer to two significa

Black_prince [1.1K]

Answer: The equilibrium concentration of $H_3O^+$ ion is $8.3064\times 10^{-2}M$

Explanation:

We are given:

Molarity of oxalic acid solution = 0.20 M

Oxalic acid $(H_2C_2O_4)$ is a weak acid and will dissociate 2 hydrogen ions.

The chemical equation for the first dissociation of oxalic acid follows:

$H_2C_2O_4(aq.)+H_2O\rightleftharpoons H_3O^+(aq.)+HC_2O_4^-(aq.)$

Initial: 0.20

At eqllm: 0.20-x x x

The expression of first equilibrium constant equation follows:

$Ka_1=\frac{[H_3O^+][HC_2O_4^{-}]}{[H_2C_2O_4]}$

We know that:

$Ka_1\text{ for }H_2C_2O_4=0.059$

Putting values in above equation, we get:

$0.059=\frac{x\times x}{(0.20-x)}\\\\x=-0.142,0.083$

Neglecting the negative value of 'x', because concentration cannot be negative.

So, equilibrium concentration of hydronium ion = x = 0.083 M

The chemical equation for the second dissociation of oxalic acid:

$HC_2O_4^-(aq.)+H_2O\rightarrow H_3O^+(aq.)+C_2O_4^{2-}(aq.)$

Initial: 0.083

At eqllm: 0.083-y 0.083+y y

The expression of second equilibrium constant equation follows:

$Ka_2=\frac{[H_3O^+][C_2O_4^{2-}]}{[HC_2O_4^-]}$

We know that:

$Ka_2\text{ for }H_2C_2O_4=6.4\times 10^{-5}$

Putting values in above equation, we get:

$6.4\times 10^{-5}=\frac{(0.083+y)\times y}{(0.083-y)}\\\\y=-0.083,0.0000639$

Neglecting the negative value of 'x', because concentration cannot be negative.

So, equilibrium concentration of hydronium ion = y = 0.0000639 M

Total concentration of hydronium ion = [x + y] = [0.083 + 0.0000639] = 0.0830639 M

Hence, the equilibrium concentration of $H_3O^+$ ion is $8.3064\times 10^{-2}M$

7 0

3 years ago

What is the mass in kilograms of an object that weighs 50.0lbs?

Aleonysh [2.5K]

The amount of matter in an object is said to be its mass. The SI base unit of mass is kilograms i.e. $kg$ .

The mass of the object = $50.0 lbs$ (given)

For converting lbs to kg:

$1 lb = 0.453592 kg$

So, $50 lbs = 50\times 0.453592 kg = 22.6796 kg \simeq 22.68 kg$

Hence, the mass of $50.0lbs$ object in kilograms is $22.68 kg$ .

5 0

3 years ago

Consider the reaction Ca(OH)2(s)→CaO(s)+H2O(l) with enthalpy of reaction ΔHrxn∘=65.2kJ/mol What is the enthalpy of formation of

Ganezh [65]

Answer:

ΔH °fCaO= -655.09 KJ/mol = ΔH °fCaO

Explanation:

ΔH °(reaction)a=ΔH °f(product)-ΔH °f(reactant)

where,

ΔH °f(product)=is the standard heat of formation of products

-ΔH °f(reactant)=is the standard heat of formation of reactants

The standard heat of formation of H 2 O ( l ) is − 285.8 k J / m o l .

The standard heat of formation of Ca(OH )2 is − 986.09 k J / m o l .

For the given reaction, the standard enthalpy change is calculated by the expression shown below.

ΔH °(reaction)a=ΔH °f(CaO+H2O)-ΔH °f(Ca(OH)₂

65.2 = ΔH °fCaO+( -265.8) -(-986.09)

= ΔH °fCaO-265.8+986.09

65.2 = ΔH °fCaO+ 720.29

65.2-720.29 = ΔH °fCaO

-655.09 KJ/mol == ΔH °fCaO

3 0

3 years ago

Chemistry an atom of strontium has at least four different isotopes. what is different between an isotope of 86sr and an isotope

lions [1.4K]

Isotopes are atoms of the same element that differ in the number of neutrons.

Remember that all the atoms of an element have the same number of protons. So the only difference between isotopes of an element is the number of neutrons.

86 Sr means that the mass number of this isotope is 86. Also, remember that the mass number is the number of protons plus the number of neutrons.

87 Sr means that the mass number of this isotope is 87.

So, 86 Sr and 87 Sr differ 1 neutron.

Answer: 1 neutron

5 0

3 years ago

The volume of a 2.49 g sample of gas is 752 mL at 1.98 atm and 62 C What is the gas?

creativ13 [48]

Answer:

The volume of a sample of gas (2.49 g) was 752 mL at 1.98 atm and 62∘C 62 ∘ C .

6 0

3 years ago