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mestny [16]
2 years ago
12

9. How many significant figures are there in the number 0.0001372?

Chemistry
2 answers:
stellarik [79]2 years ago
5 0

Answer: D. 4

Explanation:

For numbers with decimal point, we should start counting from the first number that non-zero from the left.

0.0001372

We start counting from 1, since it is the first non-zero number

1, 3, 7, 2

There are in total 4 significant figures

Hope this helps!! :)

Please let me know if you have any question or need further explanation

olga_2 [115]2 years ago
4 0
D because 0 is always ignorant in significant figures. hope that helps:)
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Taking advantage of their large differences in pKa values, describe how a mixture of phenol and benzoic acid in diethyl ether so
Marat540 [252]

Answer:

By adding bicarbonate.

Explanation:

The pka of the phenol (C₆H₅OH) is 10 and the pka of the benzoic acid (C₆H₅COOH) is 4, which means that the benzoic acid is a stronger acid than phenol, so if we want to separate phenol from benzoic acid in diethyl ether we need to first use a weak base that will react with benzoic acid and not with the phenol:  

C₆H₅-COOH + HCO₃⁻  ⇄  C₆H₅-COO⁻  +  H₂CO₃

C₆H₅-OH + HCO₃⁻  ⇄  no reaction

The reaction of the benzoic acid with bicarbonate will produce the benzoate ion that will be soluble in the aqueous layer, while the phenol will remain dissolved in the organic layer, so we can separate the two of them by the separation of the two immiscible layers.      

Having the two layers separated, the benzoic acid can be recovered from the aqueous layer by adding HCl:

C₆H₅-COO⁻ + HCl  ⇄  C₆H₅-COOH + Cl⁻

<u>This acid will precipitate from the aqueous solution, and the solid can be isolated by filtration</u>.  

The phenol in the organic layer can be dissolved into an aqueous layer by the adding of a strong base like NaOH:

C₆H₅-OH + OH⁻  ⇄  C₆H₅-O⁻ + H₂O

The phenoxide ion soluble in the aqueous layer can be recovered later by the adding of HCl, which will form the original phenol:

C₆H₅-O⁻ + HCl  ⇄  C₆H₅-OH + Cl⁻  

<u>The precipitated phenol can be isolated by filtration. </u>

This way we can separate a mixture of phenol and benzoic acid in diethyl ether solution.  

I hope it helps you!

6 0
3 years ago
g A and B are both non-volatile molecular compounds. Substance A has a greater molar mass than substance B. If 50 g of substance
Doss [256]

Answer:

The correct answer is - option D.  the boiling point of solution A will be lower than the boiling point of solution B

Explanation:

Colligative properties such as a decrease in the freezing point of the solution, increase in the boiling point of substance, decrease in Lowering of vapor pressure, and other properties depend upon the number of molecules only.

In the given solution the equal amount of two solutions are mixed that is 50 grams however due to the difference in the molecular mass so the atoms present in both solution A and B will be different. It is known that the number of atoms of a substance is inversely proportional to the molecular mass of the particular substance.

As it is given that Solution B has a low molecular mass which means it has a high number of atoms that means its boiling point will be higher than solution A.

8 0
2 years ago
A gas occupies 900.0 ML at temperatures of 27.0 Celsius. What is the volume at 123.0 celsius
Artemon [7]

Answer:

1188.0 mL.

Explanation:

  • We can use the general law of ideal gas: PV = nRT.

where, P is the pressure of the gas in atm.

V is the volume of the gas in L.

n is the no. of moles of the gas in mol.

R is the general gas constant,

T is the temperature of the gas in K.

  • If n and P are constant, and have two different values of V and T:

<em>V₁T₂ = V₂T₁ </em>

V₁ = 900 mL, T₁ = 27.0°C + 273 = 300.0 K.

V₂ = ??? mL, T₂ = 123.0°C + 273 = 396.0 K.

<em>∴ V₂ = V₁T₂/T₁ </em>= (900 mL)(396 K)/(300.0 K) = <em>1188.0 mL.</em>

4 0
3 years ago
Read 2 more answers
How many mL of a 4% mass/volume Mg(NO3)2 solution would contain 1.2 grams of magnesium nitrate?
Phoenix [80]
4% mass / volume :

4 g ---------> 100 mL
1.2 g ------- ? mL

V = 1.2 * 100 / 4

V = 120 / 4

V = 30 mL

hope this helps!

7 0
2 years ago
A patient needs 0.024 g of a sulfa drug. There are 6-mg tablets in stock. How many tablets should be given?
AfilCa [17]
0.024g=24mg
24mg/6mg=4 tablets 
4 0
3 years ago
Read 2 more answers
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