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3 years ago

The empirical formula of styrene is ch; its molar mass is 104.1 g/mol. what is the molecular formula of styrene? select one:

2 answers:

6 0

The empirical formula is a formula of a compound showing the proportion of each element involved in the compounds but it does not represent the total number of atoms in the compound. It is the lowest number of ratio between the elements in the compound. In order, to determine the actual number of the atoms or the molecular formula of the compounds, we make use of the molar mass of the compound.

<span>To determine the molecular formula, we multiply a value to the empirical formula. Then, calculate the molar mass and see whether it is equal to the one given (104.1 g/ mol). From the choices, the only valid options are b, d and e.
</span> molar mass
1 CH 13.02
8 C8H8 104.16
6 C6H6 78.12

Therefore the correct answer is option B.

geniusboy [140]3 years ago

3 0

Answer:

b. C₈H₈

Explanation:

The empirical formula of styrene is CH. To calculate the molecular formula, we have to calculate "n", where n:

$n=\frac{molar\ mass\ molecular\ formula }{molar\ mass\ empirical\ formula}$

The molar mass of the empirical formula is C + H = 12.01 + 1.00 = 13.01 g/mol

The molar mass of the molecular formula is 104.1 g/mol

n = (104.1 g/mol) / (13.01 g/mol) ≈ 8

The molecular formula is:

Molecular formula = n × Empirical formula = 8 × CH = C₈H₈

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4 years ago

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Give the ΔH value for the combustion of butane as shown in the reaction 2C4H10(g)+13O2(g)→8CO2(g)+10H2O(g)+5315 kJ.

777dan777 [17]

Answer:

ΔH = - 5315 kJ.

Explanation:

The given chemical reaction is as follows -

2C₄H₁₀ (g) + 13 O₂ (g) → 8 CO₂ (g) + 10 H₂O (g) + 5315 kJ

In the above equation , the amount of energy i.e. 5315 kJ is released , i.e. it is in the product side , hence , the reaction is an example of an exothermic reaction .

Hence ,

The value of the change in enthalphy , i.e. , the enthalpy of product minus the enthalpy of the product .

Therefore ,

The value of the change in enthalphy = - ve .

Hence ,

ΔH = - 5315 kJ.

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3 years ago

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Potassium thiocyanate, KSCN, is often used to detect the presence of Fe3+ ions in solution through the formation of the red Fe(H

Natalija [7]

Answer:

Ferric ions left in the solution at equilibrium is $8.0\times 10^{-6} M$ .

Explanation:

Moles of ferric nitrate in 0.700 L = n

Volume of the solution = V = 0.700 L

Molarity of ferric nitrate = M = 0.00150 M

$n=M\times V=0.00150 M\times 0.700 L=0.00105 mol$

Moles of potassium thiocyanate in 0.700 L = n'

Volume of the potassium thiocyanate solution = V' = 0.700 L

Molarity of potassium thiocyanate = M' = 0.200 M

$n'=M'\times V'=0.200 M\times 0.700 L=0.140 mol$

Molarity of ferric ions after mixing :

1 mol of ferric nitrate gives 1 mol of ferric ions.Then 0.00105 mol ferric nitrate will :

Moles of ferric ions = 0.00105 mol

$M_1=\frac{0.00105 mol}{0.700 L+0.700 L}=0.00075 M$

Molarity of thiocyanate ions after mixing :

1 mol of potassium thiocyanate gives 1 mol of thiocyanate ions.Then 0.140 mol potassium thiocyanate will give:

Moles of thiocyanate ions = 0.140 mol

$M_2=\frac{0.140 mol}{0.700 L+0.700 L}=0.1 M$

Complex equation:

$Fe^{3+}+SCN^-\rightleftharpoons [Fe(SCN)]^{2+}$

0.00075 M 0.1 M 0

At equilibrium:

(0.00075 M -x) (0.1 M-x) x

The formation constant of the given complex = $K_f=8.9\times 10^2$

$K_f=\frac{[[Fe(SCN)]^{2+}]}{[[Fe^{3+}]][SCN^{-}]}$

$8.9\times 10^2=\frac{x}{(0.00075 M -x)\times (0.1 M-x)}$

Solving for x:

x = 0.000742 M

Ferric ions left in the solution at equilibrium :

= (0.00075 M -x) = (0.00075 M - 0.000742 M)= $8.0\times 10^{-6} M$

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3 years ago

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AlladinOne [14]

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Explanation:

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3 years ago

How many grams are in 5.2 moles of Li2SO4

skelet666 [1.2K]

Answer:

572 g

Explanation:

Molar mass is the mass of 1 mol of an element or compound

molar mass of Li₂SO₄ is the sum of the products of the molar masses of the elements by the number of atoms in the compound

molar masses of each element making up lithium sulphate

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S - 32 g/mol

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mass of 1 mol of Li₂SO₄ is 110 g

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7 0

3 years ago