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2 years ago

Question 5 of 10

Chemistry

2 answers:

OverLord2011 [107]2 years ago

4 0

Answer:

4.2 g

Explanation:

The VOLUME of the ring is 4.2 - 4.0 = .2 ml = .2 cm^3

the MASS of the ring is this times the density

.2 cm^3 * 21 g/cm^3 = 4.2 g

Marianna [84]2 years ago

3 0

Answer:

the answer is c

Explanation:

density is mass/volume

so mass=density × volume

but we take the change is volume that is v2-v2=4.2-4=0.2ml

but the density is in gm/cm^3 so we should convert ml into cm^3. eventually they are equal so mass=21×0.2=4.2

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Please help..

Tamiku [17]

Answer:

For a 1:100 dilution, one part of the solution is mixed with 99 parts new solvent. Mixing 100 µL of a stock solution with 900 µL of water makes a 1:10 dilution. The final volume of the diluted sample is 1000 µL (1 mL), and the concentration is 1/10 that of the original solution

Explanation:

i hope that gives you an idea

4 0

3 years ago

How many grams of sodium benzoate should be added to prepare the buffer? Neglect the small volume change that occurs when the so

expeople1 [14]

Answer:

$2.72$ grams

Explanation:

Complete question is

You are asked to pre pare a pH = 4.00 buffer starting from 1.50 L of 0.0200 M solution of benzoic acid

(C6H5COOH)

and any amount you need of sodium benzoate

(C6H5COONa)

How many grams of sodium benzoate should be added to prepare the buffer? Neglect the small volume change that occurs when the sodium benzoate is added.

Solution

Given

pH of the buffer solution $= 4$

Concentration of C6H5COOH $= 0.02$ M

Volume of the buffer solution $= 1.50$ L

$K_a$ value for benzoic acid is $6.3 * 10^ {-5}$

Concentration of sodium benzoate

$pH = - log Ka + log \frac{C6H5COONa}{C6H5COOH}$

Substituting the given values we get

$log \frac{C6H5COONa}{C6H5COOH} = 4 + log (6.3 * 10^ {-5})\\log \frac{C6H5COONa}{C6H5COOH} = -0.20\\\frac{C6H5COONa}{C6H5COOH} = 10^{-0.2}\\{C6H5COONa} = 10^{-0.2} * 0.02\\{C6H5COONa} = 0.63 * 0.02\\{C6H5COONa} = 0.0126 M$

Number of moles in sodium benzoate

$= 0.0126 * 1.5 \\= 0.0189 Mol$

Mass of sodium benzoate

$0.0189 mol * 144.147 \frac{g}{mol} \\= 2.72 g$

3 0

3 years ago

What is the mass of NaCl required to make 160 grams of a 12% solution of NaCl in water?

Ksivusya [100]

Answer:

0.5

L solution

⋅

required molarity

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2.5 moles NaCl

L solution

1.25 moles NaCl

Now, to convert this to grams of sodium chloride, you must use the mass of

mole of this compound as a conversion factor. The mass of

mole of sodium chloride is given by its molar mass

1.25

moles NaCl

⋅

58.44 g

mole NaCl

73 g

−−−−

Explanation: if this is wrong i am very sorry

6 0

3 years ago

A battery contains two metals that have different tendencies to attract electrons. If one is lithium with an electron affinity o

Vitek1552 [10]

Answer:

I know that the electrons flow would be: The electrons will flow from lithium to zinc.

Explanation:

But I also dont know what would make this an even stronger battery.

4 0

3 years ago

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Which of the following is the correct formula for copper (I) sulfate trihydrate? CuSO4 · 3H2O

PilotLPTM [1.2K]

It is either the 3rd answer or the 4th answer. Both are correct ways to write hydrates, but I was taught the 4th way. Just make sure this answer matches the format of the examples your teacher gave you.

6 0

3 years ago

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