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3 years ago

If I have 2mol NaOH in 3L solution, what is the molarity of my solution

1 answer:

4 0

Molarity is defined as the number of moles dissolved in 1 L of solution .2 mol of NaOH has been dissolved in a volume of 3 L.
we need to then find the number of NaOH moles dissolved in 1 L.
Molarity = number of moles / volume in L
Molarity = 2 mol / 3 L = 0.67 mol/L
Therefore molarity of NaOH - 0.67 M

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A chemist titrates of a hypochlorous acid solution with solution at . Calculate the pH at equivalence. The of hypochlorous acid

const2013 [10]

The question is incomplete, here is the complete question:

A chemist titrates 110.0 mL of a 0.2412 M hypochlorous acid (HCIO) solution with 0.0613 M NaOH solution at 25°C. Calculate the pH at equivalence. The pKa of hypochlorous acid is 7.50. Round your answer to 2 decimal places

Answer: The pH of the solution is 10.09

Explanation:

To calculate the volume of base, we use the equation given by neutralization reaction:

$n_1M_1V_1=n_2M_2V_2$

where,

$n_1,M_1\text{ and }V_1$ are the n-factor, molarity and volume of acid which is $HClO$

$n_2,M_2\text{ and }V_2$ are the n-factor, molarity and volume of base which is NaOH.

We are given:

$n_1=1\\M_1=0.2412M\\V_1=110.0mL\\n_2=1\\M_2=0.0613M\\V_2=?mL$

Putting values in above equation, we get:

$1\times 0.2412\times 110.0=1\times 0.0613\times V_2\\\\V_2=\frac{1\times 0.2412\times 110.0}{1\times 0.0613}=432.8mL$

At equivalence, the number of moles of acid is equal to the number of moles of base. Also, the moles of salt which is NaClO will also be the same.

To calculate the number of moles for given molarity, we use the equation:

$\text{Molarity of the solution}=\frac{\text{Moles of solute}\times 1000}{\text{Volume of solution (in mL)}}$ .....(1)

For HClO:

Molarity of HClO solution = 0.2412 M

Volume of solution = 110.0 mL

Putting values in equation 1, we get:

$0.2412M=\frac{\text{Moles of HClO}\times 1000}{110}\\\\\text{Moles of HClO}=\frac{(0.2412\times 110)}{1000}=0.026532mol$

For NaClO:

Moles of NaClO = 0.026532 moles

Volume of solution = [432.8 + 110] mL = 542.8 mL

Putting values in above equation, we get:

$\text{Molarity of NaClO}=\frac{0.026532\times 1000}{542.8}=0.0489M$

To calculate the pH of the solution, we use the equation:

$pH=7+\frac{1}{2}[pK_a+\log C]$

where,

$pK_a$ = negative logarithm of weak acid which is hypochlorous acid = 7.50

C = concentration of the salt = 0.0489 M

Putting values in above equation, we get:

$pH=7+\frac{1}{2}[7.50+\log (0.0489)]\\\\pH=7+3.09=10.09$

Hence, the pH of the solution is 10.09

4 0

3 years ago

What is the concentration of bromide, in ppm, if 12.41 g MgBr2 is dissolved in 2.55 L water.

pav-90 [236]

Answer:

concentration of bromide (Br⁻) = 4234 mg/L = 4234 ppm

Explanation:

ppm (parts per million) concentration is defined as the mass (in milligrams) of a substance dissolved in one liter of solution.

In our case we have:

mass of MgBr₂ = 12.41 g

volume of water (which is equal to the final solution volume) = 2.55 L

Now we devise the following reasoning:

if 12.41 g of MgBr₂ are dissolved in 2.55 L of water

then X g of MgBr₂ are dissolved in 1 L of water

X = (1 × 12.41) / 2.55 = 4.867 g of MgBr₂

if in 184 g (1 mole) of MgBr₂ we have 160 g of Br⁻

then in 4.867 g of MgBr₂ we have Y g of Br⁻

Y = (4.867 × 160) / 184 = 4.232 g of bromide (Br⁻)

4.232 g of bromide (Br⁻) = 4234 mg of bromide (Br⁻)

concentration of bromide (Br⁻) = 4234 mg/L = 4234 ppm

7 0

4 years ago

Rolls of foil are 302 mm wide and 0.018 mm thick. (The density of foil is 2.7 g/cm3 .)

Kruka [31]

Answer:

The length of foil will be 8107.81 cm or 81.7081 m.

Explanation:

Given data:

Width of roll of foil = 302 mm

Height or thickness = 0.018 mm

Density of foil = 2.7 g/cm³

Mass of foil = 1.19 Kg

Length of foil = ?

Solution:

d = m/ v

v = length (l) × width (w) × height (h)

First of we will convert the Kg into gram and mm into cm.

one Kg = 1000 g

1.19 × 1000 = 1190 g

one cm = 10 mm

302 / 10 = 30.2 cm

0.018 / 10 = 0.0018 cm

Now we will put the values in formula:

d = m/ l× h× w

l = m / d × h× w

l = 1190 g / 2.7 g/cm³× 30.2 cm × 0.0018 cm

l = 1190 g/ 0.146772 g/cm

l = 8107.81 cm or 81.7081 m

3 0

3 years ago

Please tell if my answer is right or wrong.

xxTIMURxx [149]

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5 0

3 years ago

A very loud sound has a high _____.

DENIUS [597]

Answer:

Resting Point

Explanation:

4 0

3 years ago

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