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3 years ago

Calculation of Percent Composition

Chemistry

1 answer:

Trava [24]3 years ago

6 0

Answer:

C: 61.0%, H: 15.3%, N: 23.7%

Explanation:

We can calculate the percent by mass of each element using the following expression.

%Element = (mass of the element/mass of the compound) × 100%

Carbon

%C = (7.34 g/12.04 g) × 100% = 61.0%

Hydrogen

%H = (1.85 g/12.04 g) × 100% = 15.3%

Nitrogen

%N = (2.85 g/12.04 g) × 100% = 23.7%

The percent composition of this compound is C: 61.0%, H: 15.3%, N: 23.7%.

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Which of the following best describes an atom? For science

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4 years ago

Describe in detail how to prepare 500.0 mL of a 2.5 M calcium chloride solution. Calcium chloride is purchased as a solid. TO pi

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Answer:

In a volumetric flask of marking 500.0 mL add 138.75 grams of calcium chloride and add small amount of water to dissolve solute completely. After the solute gets completely soluble add more water up till the mark of 500 ml.

Explanation:

Concentration of calcium chloride = 2.5 M

Volume of the solution = 500.0 ml = 0.5000 L

Moles of calcium chloride = n

$c=\frac{n}{V(L)}$

n = moles of solute

c = concentration of solution

V = volume of the solution in L

$2.5 M=\frac{n}{0.5000 L}$

$n=2.5 M\times 0.5000 L = 1.2500 mol$

$n=\frac{\text{Mass of calcium chloride}}{\text{Molar mass of calcium chloride}}$

$1.2500 mol=\frac{\text{Mass of calcium chloride}}{111 g/mol}$

Mass of calcium chloride = 111 g/mol × 1.2500 mol = 138.75 g

In a volumetric flask of marking 500.0 mL add 138.75 grams of calcium chloride and add small amount of water to dissolve solute completely. After the the solute gets completely soluble add more water up till the mark of 500 ml.

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3 years ago

Choose the compound below that should have the highest melting point according to the ionic bonding model. Choose the compound b

Bingel [31]

Answer:

AlN has highest melting point among given.

Explanation:

As per ionic model, ionic compounds are held together by electrostatic force. The ionic compound having strong electrostatic force will have high melting point.

Electrostatic force is proportional to charge and size of constituent ions.

$F=k \frac{q_+\times q_-}{r^2}$

In case of MgO

Charge on Mg = +2

Charge on O = -2

$F=-k \frac{(+2)\times (--2)}{r^2}=\frac{4k}{r^2}$

In case of LiF

Charge on Li = +1

Charge on F = -1

$F=-k \frac{(+1)\times (-1)}{r^2}=\frac{1k}{r^2}$

In case of AlN

Charge on Al = +3

Charge on N = -3

$F=-k \frac{(+3)\times (-3)}{r^2}=\frac{9k}{r^2}$

In case of RbF

Charge on Rb = +1

Charge on F = -1

$F=-k \frac{(+1)\times (-1)}{r^2}=\frac{1k}{r^2}$

In case of CaS

Charge on Ca = +2

Charge on S = -2

$F=-k \frac{(+2)\times (-2)}{r^2}=\frac{4k}{r^2}$

As magnitude of electrostatic force is highest in AlN, therefor, it has highest melting point.

4 0

3 years ago