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3 years ago

A 1300 mL sample of gas with a molar mass of 71.0 g/mol at STP has what density?

Chemistry

1 answer:

Blizzard [7]3 years ago

6 0

Answer:

0.055g/mL

Explanation:

Data obtained from the question include:

Molar Mass of the gass sample = 71g/mol

Volume of the gas sample = 1300 mL

Density =?

The density of a substance is simply mass per unit volume. It is represented mathematically as:

Density = Mass /volume.

With the above equation, we can easily obtain the density of sample of gas as illustrated below:

Density = 71g / 1300 mL

Density = 0.055g/mL

Therefore, the density of the gas sample is 0.055g/mL

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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

How many moles of sulfur dioxide are in 2.26 x 10^33 sulfur dioxide molecules?

LUCKY_DIMON [66]

Answer:

moles = no. of molecules / Avogadro's number

= 2.26 x 10^33 / 6.022 x 10^23

= 3752906011

Round to significant figures which is 3 = 3.75 x 10^9 mol

Explanation: The formula for finding how many moles of a substance when given the amount of molecules is: moles = number of molecules / Avogadro's number

6 0

3 years ago

Calculate the molar mass of cacl2

kirza4 [7]

Answer:

$\boxed {\boxed {\sf 110.98 \ g/mol}}$

Explanation:

The molar mass is the mass of a substance in grams per mole.

To find it, add the mass of each element in the compound. These masses can be found on the Periodic Table.

The compound given is:

$CaCl_2$

The compound has 1 Ca (calcium) and 2 Cl (chlorine).

Mass of Calcium

The molar mass of calcium is 40.08 g/mol
There is only one atom of Calcium in CaCl₂, so the number above is what we will use.

Mass of Chlorine

The molar mass of chlorine is 35.45 g/mol
There are two atoms of chlorine in CaCl₂, therefore we need to multiply the molar mass by 2.
35.45 * 2= 70.9 g/mol

Molar Mass of CaCl₂

Now, to find the molar mass, add the molar mass of 1 calcium and 2 chlorine.
40.08 g/mol + 70.9 g/mol =110.98 g/mol

The molar mass of CaCl₂ is 110.98 grams per mole.

6 0

3 years ago

PLEASE HELP I got this wrong on an exam but got it wrong and i don’t know why!

lord [1]

Answer:

D.5,55cm+/-0,005cm

Explanation:

so this is the answer

5 0

3 years ago

the average speeds of gas molecules in.cylinders A,b,c,d are 0.01 m/s, 0.005m/s ,0.1 m/s and 0.5 m/s, respectively .which cylind

Darya [45]

The average speed of the gas is related to the kinetic energy of the gas. The kinetic energy of the gas is also related to the temperature of the gas. If the average speed of the gas is closer to zero, it means that it has very low motion or kinetic energy. This can be inferred that the gas has a very low temperature. At absolute zero, the motion of all the gas molecules stops. This means that the kinetic energy of the gas is also zero. Zero kinetic energy means zero average speed. So, the answer is cylinder B. The average speed of the gas in cylinder B is closest to zero.

8 0

3 years ago