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lawyer [7]
3 years ago
5

When 4.979 grams of a hydrocarbon, CxHy, were burned in a combustion analysis apparatus, 16.20 grams of CO2 and 4.976 grams of H

2O were produced.
In a separate experiment, the molar mass of the compound was found to be 54.09 g/mol. Determine the empirical formula and the molecular formula of the hydrocarbon.
Chemistry
1 answer:
dimaraw [331]3 years ago
5 0
For Hydrocarbon combustion:

CₓHₐ + O₂ → xCO₂ + a/2 H₂O

Moles of CO₂ = 16.2 / 44 = 0.37
Moles of Carbon = 0.37
Moles of H₂O = 4.976 / 18 = 0.28
Moles of Hydrogen = 0.28 x 2 = 0.56

Molar ratio = C : H = 1 : 1.5
= 2 : 3
C₂H₃

Mass of empirical unit = 12 x 2 + 1 x 3
= 27
Mr = 54.09
Number of empirical units repeated: 54.09 / 27
= 2

Molecular formula = C₄H₆
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Calculate the molar solubility of fe(oh)2 in pure water. (the value of ksp for fe(oh)2 is 4.87×10−17.)
rosijanka [135]
When we have this balanced equation for a reaction:
Fe(OH)2(s) ↔ Fe+2  + 2OH-

when Fe(OH)2 give 1 mole of Fe+2 & 2 mol of OH-
so we can assume [Fe+2] = X and [OH-] = 2 X
 when Ksp = [Fe+2][OH-]^2
and have Ksp = 4.87x10^-17 
[Fe+2]= X
[OH-] = 2X
so by substitution 
4.87x10^-17 = X*(2X)^2
∴X^3 = 4.8x10^-17 / 4
∴the molar solubility X = 2.3x10^-6 M
3 0
3 years ago
Which statement below can NOT
alexandr402 [8]

Answer:

the answer is B:

Explanation:

I hope it help.

6 0
3 years ago
Homework 1
Bond [772]

Answer:

average for silk =141"

average for cotton =96"

average for nylon = 70"

if you desire a slower falling parachute to protect the body from damage,

silk is the best

if you desire a faster falling parachute to escape enemy bullets,

nylon is the best

Explanation:

Homework 1

Problem Solving

1. Kelvin and Xavier were doing an investigation on parachutes. One of them suggested that the type of material the parachute was made from had an effect on how long it took to reach the ground. Their results are given in

the table below.

(a) Calculate the average time in seconds for each material.

Time taken for parachute to reach the ground (seconds)

MATERIAL

1st TRY

2nd TRY

3rd TRY

AVERAGE

Sik

144

140  average of 3 = 141

139

Cotton

98

96   average of 3  = 96

94

Nylon

72

68    average of 3 = 70

70

5 0
2 years ago
The molar heat of vaporization of water is 40.7kJ/mol. How much heat must be absorbed to convert 50.0 grams of liquid water at 1
EleoNora [17]
During a phase change the temperature does not change since all of the heat is being absorbed in order to break the intermolecular forces.  Due to that, the formula will not need to have T in it and is actually q=nΔH(v).
n=the number of moles (in this case 2.778mol of water since you divide 50g by 18g/mol).
ΔH(v)=the molar heat of vaporization (in this case 40.7kJ/mol).
q=the heat that must be absorbed
q=2.778mol×40.7kJ/mol
q=113.1kJ
Therefore the water needs to absorb 1.13×10²kJ.

I hope this helps.  Let me know if anything is unclear.

4 0
3 years ago
What is the ph of a 0.0055 m ha (weak acid) solution that is 8.2% ionized?
Trava [24]
Answer is: pH value of weak is 3.35.
Chemical reaction (dissociation): HA(aq) → H⁺(aq) + A⁻(aq).
c(HA) = 0.0055 M.
α = 8.2% ÷ 100% = 0.082.
[H⁺] = c(HA) · α.
[H⁺] = 0.0055 M · 0.082.
[H⁺] = 0.000451 M.
pH = -log[H⁺].
pH = -log(0.000451 M).
pH = 3.35.
pH (potential of hydrogen) is a numeric scale used to specify the acidity or basicity <span>an aqueous solution.</span>
3 0
3 years ago
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