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3 years ago

Determine the pH of a KOH solution made by mixing 0.251 g KOH with enough water to make 1.0 × 10 2 mL of solution

Chemistry

1 answer:

vesna_86 [32]3 years ago

6 0

Answer:

pH = 12.65

Explanation:

From the given information:

number of moles =mass in gram / molar mass

number of moles of KOH = mass of KOH / molar mass of KOH

number of moles of KOH = 0.251 g / 56.1 g/mol = 0.004474 mol

For solution :

number of moles = Concentration × volume

concetration = number of moles/ volume

concetration = 0.004474 mol / 0.100 L

concetration = 0.04474 M

We know that 1 moles KOH result into 1 mole OH⁻ ions

Therefore, Molarity of OH⁻ = 0.04474 M

Now,

pOH = -log[OH⁻]

pOH = -log (0.04474) M

pOH = 1.35

Similarly,

pH + pOH = 14

pH = 14 - pOH

pH = 14 - 1.35

pH = 12.65

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A 25 liter gas cylinder contains 10 mole of carbon dioxide. Calculate the pressure, in atm, of the gas at 325K.

Arada [10]

Answer: The pressure of carbon dioxide gas is 11 atm

Explanation:

To calculate the pressure of gas, we use the equation given by ideal gas equation:

PV = nRT

where,

P = pressure of the gas = ?

V = Volume of gas = 25 L

n = number of moles of gas = 10 mole

R = Gas constant = $0.0821\text{ L atm }mol^{-1}K^{-1}$

T = temperature of the gas = 325 K

Putting values in above equation, we get:

$P\times 25L=10mol\times 0.0821\text{ L atm }mol^{-1}K^{-1}\times 325K\\\\P=11atm$

Hence, the pressure of carbon dioxide gas is 11 atm

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3 years ago

Balance the equation below Fe, Fe+ 02

Katena32 [7]

2 Fe2O5-> 4 Fe+ 5 O2

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3 years ago

The fact that HBO2, a reactive compound, was produced rather than the relatively inert B2O3 was a factor in the discontinuation

Reil [10]

Answer:

1027.62 g

Explanation:

For $B_2H_6$ :-

Mass of $B_2H_6$ = 296.1 g

Molar mass of $B_2H_6$ = 27.66 g/mol

The formula for the calculation of moles is shown below:

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

Thus,

$Moles= \frac{296.1\ g}{27.66\ g/mol}$

$Moles\ of\ B_2H_6= 10.705\ mol$

From the balanced reaction:-

$B_2H_6(g) + 3 O2_{(l)}\rightarrow 2 HBO_2_{(g)}+ 2 H_2O_{(l)}$

1 mole of $B_2H_6$ react with 3 moles of oxygen

Thus,

10.705 mole of $B_2H_6$ react with 3*10.705 moles of oxygen

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8 0

3 years ago

What is the pH of 0.30 M ethanolamine, HOCH2CH2NH2, (Kb = 3.2 x 10−5)?

Dmitry [639]

Answer:

pH= 11.49

Explanation:

Ethanolamine is an organic chemical compound of the formula; HOCH2CH2NH2. Ethanolamine, HOCH2CH2NH2 is a weak base.

From the question, the parameters given are; the concentration of ethanolamine which is = 0.30M, pH value= ??, pOH value= ??, kb=3.2 ×10^-5

Using the formula below;

[OH^-]=√(kb×molarity)----------------------------------------------------------------------------------------------------------(1)

[OH^-] =√(3.2×10^-5 × 0.30M)

[OH^-]= √(9.6×10^-6)

[OH^-]=3.0984×10^-3

pOH= -log[OH^-]

pOH= -log 3.1×10^-3

pOH= 3-log 3.1

pH= 14-pOH

pH= 14-(3-log3.1)

pH= 11+log 3.1

pH= 11+ 0.4914

pH= 11.49

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3 years ago

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user100 [1]

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5 0

3 years ago

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