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3 years ago

What is the concentration of hydroxide ions in pure water at 30.0 ∘C, of Kw at this temperature is 1.47x10-14?

Chemistry

1 answer:

klio [65]3 years ago

7 0

Answer:

[OH⁻] = 1.21×10⁻⁷

Explanation:

Water dissociates in the solution as:

H₂O ⇔ H⁺ + OH⁻

For pure water, the concentration of [H⁺] and [OH⁻] are equal.

Kw is defined as the product of the active concentration of H⁺ and OH⁻ furnished by the water.

So,

Kw = [H⁺] [OH⁻]

Given that, at 30.0 °C, the Kw is 1.47×10⁻¹⁴

So,

Kw = [H⁺] [OH⁻]

As stated above, [H⁺] = [OH⁻]

1.47×10⁻¹⁴ = [OH⁻]²

[OH⁻] = 1.21×10⁻⁷

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Think about what would happen if this substance were first in the solid phase, then melted in a liquid. What can you say about t

alexira [117]

Answer:

The melting point of the solid is higher in temperature then it is compared to the freezing point of the liquid.

Explanation:

3 0

3 years ago

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

I really need help pls, will pay anything

Triss [41]

Explanation:

For the first part,

Reaction equation:

N₂ + 3H₂ → 2NH₃

Given:

Number of moles of NH₃ = 6 moles

Unknown:

Number of moles of N₂ = ?

Solution:

N₂ + 3H₂ → 2NH₃;

From the reaction above, we solve from the known specie to the unknown. Ensure that the equation is balanced;

2 moles of NH₃ is produced from 1 mole of N₂

6 moles of NH₃ will be produced from $\frac{6}{2}$ mole of N₂

= 3moles of N₂

The number of moles of N₂ is 3 moles

ii.

Given parameters:

Number of moles of sulfur = 2.4moles

Molar mass of sulfur = 32.07g/mol

Unknown:

Mass of sulfur = ?

Solution:

The number of moles of any substance can be found using the expression below;

Number of moles = $\frac{mass}{molar mass}$

Mass of sulfur = number of moles of sulfur x molar mass

Insert the parameters and solve;

Mass of sulfur = 2.4 x 32.07 = 76.97g

6 0

3 years ago

Which material does not melt at any temperature?

lord [1]

Answer: Option (c) is the correct answer.

Explanation:

Wood is a mixture of different substances. Primarily it consists of cellulose, lignin, water etc.

When we heat wood then all these substance oxidize into the atmosphere even before they could melt.

Whereas iron, sodium chloride and ethanol all are the substances which can melt at any temperature.

Thus, we can conclude that out of the given options, wood, a mixture of different substances is a material that does not melt at any temperature.

6 0

3 years ago

< please help!!! >

svlad2 [7]

Answer:

n = 0.573mol

Explanation:

PV = nRT => n = PV/RT

P = 1.5atm

V = 8.56L

R = 0.08206Latm/molK

T = 0°C = 273K

n = (1.5atm)(8.56L)/(0.08206Latm/molK)(273K) = 0.573mol

8 0

3 years ago