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sineoko [7]
3 years ago
9

2) Calculate the mass(g) of the following substances: b) 0.119 mole MgCl2

Chemistry
1 answer:
VARVARA [1.3K]3 years ago
4 0

Answer:

MgCl2 = 24 + 2(35.5)

= 95

mass of substance = mol × molar mass

= 0.119 × 95

= 11.305 g

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The analysis of a hydrocarbon revealed that it was 85.7% C and 14.3% H by mass. When 1.77 g of the gas was stored in a 1.500-L f
gtnhenbr [62]

Answer:

The formula of hydrocarbon = C_3H_6

Explanation:

Moles =\frac {Given\ mass}{Molar\ mass}

% of C = 85.7

Molar mass of C = 12.0107 g/mol

% moles of C = 85.7 / 12.0107 = 7.14

% of H = 14.3

Molar mass of H = 1.00784 g/mol

% moles of H = 14.3 / 1.00784 = 14.19

Taking the simplest ratio for C and H as:

7.14 : 14.19 = 1 : 2

The empirical formula is = CH_2

Also, Given that:

Pressure = 508 Torr

Temperature = 17 °C

The conversion of T( °C) to T(K) is shown below:

T(K) = T( °C) + 273.15  

So,  

T = (17 + 273.15) K = 290.15 K  

Volume = 1.500 L

Using ideal gas equation as:

PV=nRT

where,  

P is the pressure

V is the volume

n is the number of moles

T is the temperature  

R is Gas constant having value = 62.3637 L.torr/K.mol

Applying the equation as:

508 Torr × 1.500 L = n × 62.3637 L.torr/K.mol × 290.15 K  

⇒n = 0.0421 moles

Given that :  

Amount  = 1.77 g

Molar mass = ?

The formula for the calculation of moles is shown below:

moles = \frac{Mass\ taken}{Molar\ mass}

Thus,

0.0421\ moles= \frac{1.77\ g}{Molar\ mass}

Molar mass of the hydrocarbon = 42.04 g/mol

Molecular formulas is the actual number of atoms of each element in the compound while empirical formulas is the simplest or reduced ratio of the elements in the compound.

Thus,  

Molecular mass = n × Empirical mass

Where, n is any positive number from 1, 2, 3...

Mass from the Empirical formula = 1×12 + 2×1= 14 g/mol

Molar mass = 42.04 g/mol

So,  

Molecular mass = n × Empirical mass

42.04 = n × 14

⇒ n = 3

<u>The formula of hydrocarbon = C_3H_6</u>

5 0
3 years ago
Question 4 options: what is the volume of 1.2 moles of water vapor at stp?
Law Incorporation [45]
What is the volume of 1.2 moles of water vapor at STP?
The answer is 26.9
3 0
3 years ago
Conduction is a method of energy transfer within Earth’s systems. Describe an example of conduction, including where the energy
Varvara68 [4.7K]

Answer:

Conduction is the transfer of thermal energy from one molecule to another within an object. Conduction also happens between two objects in direct contact if they have different temperatures. The hotter molecule vibrates because of the added heat. This vibration and movement transfer the energy to the surrounding molecules. The transfer of energy continues until all the molecules have the same temperature.

Conduction takes place in solids, liquids, and gases. However, it happens fastest in solids because the molecules in solids are closely packed.

8 0
3 years ago
Calculate the standard potential, e°, for this reaction from its equilibrium constant at 298 k. 6.47 x 10^5
Elina [12.6K]
The working equation for this is written below:

E° = 0.0592logK/n

So, we have to know the value of n first which represents the number of moles electron in the reaction. We cannot answer this because we are not given with the reaction. However, just suppose the reaction is:

Cu⁺ + 2e⁻ --> Cu

Then, n=2. Continuing,

E° = 0.0592log(6.47×10⁵)/2 =<em> 0.172 V</em>
4 0
3 years ago
Phenol is a compound that contains 76.57% carbon, 6.43% hydrogen, and 17.0% oxygen. Calculate the empirical formula.
Ulleksa [173]

Answer:

C₆H₆O

Explanation:

The given values are the percentage in mass of each element. Empirical formula is the simplest ratio of atoms presents in a molecule. Thus, the first we need to do is convert this percentage to mass using molar mass of each element:

<em>Moles C:</em>

76.57C * (1mol / 12g) = 6.38 moles C

<em>Moles H:</em>

6.43 * (1mol / 1g) = 6.43 moles H

<em>Moles O:</em>

17.0% * (1mol / 16g) = 1.06 moles O

Dividing each number of moles in the moles of O (The minimum number of moles. Used to obtain "The simplest ratio..."):

C = 6.38 moles C / 1.06 moles O = 6

H = 6.43 moles H / 1.06 moles O = 6

O = 1.06 moles O / 1.06 moles O = 1

That means empirical formula of phenol is:

<h3>C₆H₆O</h3>

3 0
3 years ago
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