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3 years ago

Which enthalpy change (î"h) is correct for a substance changing from the liquid phase to the solid phase?

1 answer:

7 0

I believe this should be the enthalpy of fusion. Enthalpy change is the amount of heat evolved or absorbed in a reaction. Enthalpy of fusion also called the heat of fusion resulting from providing heat energy or release of energy to a specific amount of a substance to change from solid state to liquid, without change in temperature.

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What is the volume of 1.60 grams of O2 gas at STP? (5 points)

tiny-mole [99]

Answer:

1.12 liters

Explanation:

Calculating number of moles

Molar mass of O₂ = 32 g
n = Given weight / Molar mass
n = 1.6/32
n = 0.05 moles

At STP

One mole of O₂ occupies 22.4 L
Therefore, 0.05 moles will occupy :
22.4 L x 0.05 = 1.12 L

5 0

2 years ago

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When 0.42 g of a compound containing C, H, and O is burned completely, the products are 1.03 g CO2 and 0.14 g H2O. The molecular

Luda [366]

Answer: The empirical and molecular formula for the given organic compound is $C_2H_2O_4$ and $C_6H_4O_2$

Explanation:

The chemical equation for the combustion of hydrocarbon having carbon, hydrogen and oxygen follows:

$C_xH_yO_z+O_2\rightarrow CO_2+H_2O$

where, 'x', 'y' and 'z' are the subscripts of Carbon, hydrogen and oxygen respectively.

We are given:

Mass of $CO_2=1.03g$

Mass of $H_2O=0.14g$

We know that:

Molar mass of carbon dioxide = 44 g/mol

Molar mass of water = 18 g/mol

For calculating the mass of carbon:

In 44g of carbon dioxide, 12 g of carbon is contained.

So, in 1.03 g of carbon dioxide, $\frac{12}{44}\times 1.03=0.28g$ of carbon will be contained.

For calculating the mass of hydrogen:

In 18g of water, 2 g of hydrogen is contained.

So, in 0.14 g of water, $\frac{2}{18}\times 0.14=0.016g$ of hydrogen will be contained.

Mass of oxygen in the compound = (0.42) - (0.28 + 0.016) = 0.124 g

To formulate the empirical formula, we need to follow some steps:

Step 1: Converting the given masses into moles.

Moles of Carbon = $\frac{\text{Given mass of Carbon}}{\text{Molar mass of Carbon}}=\frac{0.28g}{12g/mole}=0.023moles$

Moles of Hydrogen = $\frac{\text{Given mass of Hydrogen}}{\text{Molar mass of Hydrogen}}=\frac{0.016g}{1g/mole}=0.016moles$

Moles of Oxygen = $\frac{\text{Given mass of oxygen}}{\text{Molar mass of oxygen}}=\frac{0.124g}{16g/mole}=0.00775moles$

Step 2: Calculating the mole ratio of the given elements.

For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 0.00775 moles.

For Carbon = $\frac{0.023}{0.00775}=2.96\approx 3$

For Hydrogen = $\frac{0.016}{0.00775}=2.06\approx 2$

For Oxygen = $\frac{0.00775}{0.00775}=1$

Step 3: Taking the mole ratio as their subscripts.

The ratio of C : H : O = 3 : 2 : 1

Hence, the empirical formula for the given compound is $C_3H_{2}O_1=C_3H_2O$

For determining the molecular formula, we need to determine the valency which is multiplied by each element to get the molecular formula.

The equation used to calculate the valency is :

$n=\frac{\text{molecular mass}}{\text{empirical mass}}$

We are given:

Mass of molecular formula = 108.10 g/mol

Mass of empirical formula = 54 g/mol

Putting values in above equation, we get:

$n=\frac{108.10g/mol}{54g/mol}=2$

Multiplying this valency by the subscript of every element of empirical formula, we get:

$C_{(3\times 2)}H_{(2\times 2)}O_{(1\times 2)}=C_6H_4O_2$

Thus, the empirical and molecular formula for the given organic compound is $C_3H_2O$ and $C_6H_4O_2$

6 0

3 years ago

Please help im really stressed and doing 2 tests at the same time

DanielleElmas [232]

The answer is A, good luck

7 0

3 years ago

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Which model of the Adam was modeled after the solar system

Fofino [41]

. After Rutherford's model was published, a Danish scientist named Niels Bohr became interesting in the orbits of the electrons. He was inspired by thinking of atoms as tiny Solar Systems, where the elect

5 0

3 years ago

When you have a cold and are infected with the influenza virus, are you the host or the parasite? Host or Parasite

ololo11 [35]

Answer:

host

Explanation:

the virus exploits your cells

3 0

3 years ago

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