Which of the following measures of concentration changes with temperature?

The pH of a solution is measured eight times by one operator using the same instrument. She obtains the following data: 7.15, 7.

sergiy2304 [10]

Answer:

7.186

Explanation:

The mean is the average of some given data from a sample point.

To calculate the mean, we use the formula below:

Mean = ∑fx/∑f

Where f = frequency

x = sample data

From the given pH of the solutions, we can form a table:

x f fx

7.15 1 7.15

7.16 1 7.16

7.18 1 7.18

7.19 1 7.19

7.20 3 21.6

7.21 1 7.21

Now ∑fx = 7.15 +7.16 +7.18 + 7.19 + 7.20 + 7.21 = 57.49

∑f = 1 + 1 + 1 + 1 + 3 + 1 = 8

The mean = $\frac{57.49}{8}$ = 7.18625 = 7.186

3 0

3 years ago

If a volume of gas 177.6mL was collected at a temperature of 25.8C and the pressure is 799.7 torr, what is the original concentr

Step2247 [10]

Answer:

The original concentration of the acid was 0.605 M

Explanation:

Step 1: Data given

Volume of gas = 177.6 mL = 0.1176 L

Temperature = 25.8 °C = 298.95 K

Pressure = 799.7 torr = 799.7/ 760 = 1.0522368 atm

Volume of acid needed to react = 12.6 mL = 0.0126 L

Step 2: Calculate moles

p*V = n*R*T

n = (p*V)/(R*T)

⇒with n = the number of moles = TO BE DETERMINED

⇒with p = the pressure of the gas = 799.7 torr = 1.0522368 atm

⇒with V = the volume of the gas = 177.6 mL = 0.1776 L

⇒with R = the gas constant = 0.08206 L*atm/mol*K

⇒with T = the temperature = 25.8 °C = 298.95 K

n = 0.007618 moles

Step 3: Calculate original concentration

We need 0.007618 moles of acid to react with the same amount of moles gas

Concentration acid = moles / volume

Concentration acid = 0.007618 moles / 0.0126 L

Concentration acid = 0.605 M

The original concentration of the acid was 0.605 M

5 0

3 years ago

compared to maximum number of electrons that can occupy the d sublevel the max number of electrons that can occupy s sublevel

morpeh [17]

D-sublevel can occupy 10 electrons whereas s-sublevel can occupy 2 electrons...

5 0

3 years ago

A tablet of Pain Be Gone Aspirin, which had a mass of 1.213 g, was pulverized and 1.159 g were dissolved in 10.0 mL of ethyl alc

Elan Coil [88]

Answer:

a. Moles of $NaOH$ = 0.001643 moles

b. 0.296 g

c. 0.3098 g

d. Not acceptable

Explanation:

a.

Considering:

$Molarity=\frac{Moles\ of\ solute}{Volume\ of\ the\ solution}$

Or,

$Moles =Molarity \times {Volume\ of\ the\ solution}$

Given :

For $NaOH$ :

Molarity = 0.1052 M

Volume = 15.62 mL

The conversion of mL to L is shown below:

1 mL = 10⁻³ L

Thus, volume = 15.62×10⁻³ L

Thus, moles of $NaOH$ :

$Moles=0.1052 \times {15.62\times 10^{-3}}\ moles$

Moles of $NaOH$ = 0.001643 moles

b.

The reaction of NaOH with the acetylsalicylic acid is in the ratio of 1:1.

Thus, Moles of NaOH = Moles of acetylsalicylic acid = 0.001643 moles

Molar mass of acetylsalicylic acid = 180.16 g/mol

The formula for the calculation of moles is shown below:

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

Thus,

Mass = Moles * Molar mass = 0.001643 moles * 180.16 g/mol = 0.296 g

c.

1.159 g of sample contains 0.296 g of acetylsalicylic acid

1.213 g of sample contains $\frac{0.296}{1.159}\times 1.213$ g of acetylsalicylic acid

Mass of acetylsalicylic acid = 0.3098 g = 309.8 mg

d. Sample contains = 309.8 mg

Manufacturer claiming = 315 mg to 335 mg

Thus , it is not acceptable.

5 0

3 years ago

Which of the following is a mixture of substances?

Stels [109]

Answer:

the answer is c

b/c contain more than one element

7 0

3 years ago