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2 years ago

8

For which of the following activities might you want to hire a chemist?

2 answers:

worty [1.4K]2 years ago

7 0

For which of the following activities might you want to hire a chemist?

Answer: D. testing a rock sample for gold content

Which of the following procedures involves a physical change in one of the substances?

Answer: C. separating a salt solution by evaporating the water

Crank2 years ago

6 0

A. examining the structure of plant cells

Incorrect. A biologist is required.

B. building a fence

Incorrect. A carpenter is required.

C. building a wood storage shed

Incorrect. A carpenter is required.

D. testing a rock sample for gold content

Incorrect. A chemist is required.

A. creating salt by reacting sodium metal and chlorine gas

Incorrect. This is a chemical change as a new product is formed.

B. allowing a nail rust

Incorrect. This is a chemical change as it is the oxidation of iron to form iron oxide, rust.

C. separating a salt solution by evaporating the water

Correct. This is a physical change as salt gets separated from water and no new product is formed.

D. building a model rocket propelled by mixing baking soda and vinegar

Incorrect. This is a chemical change.

You might be interested in

How to convert butanoic acid to propanamide?

netineya [11]

Butanoic acid is converted to propanamide by first converting it to propanoic acid, then ammonium propanoate and then finally propanamide by heating.

<h3>How are carboxylic acids converted to amides?</h3>

Carboxylic acids are converted to amides by converting them into into an ammonium salt which then produces an amide on heating.

The ammonium salt is prepared by adding ammonium carbonate to an excess of the acid. The ammonium salt is then heated to give the amide

Therefore, butanoic acid is converted to propanamide by first converting it to propanoic acid, then ammonium propanoate and then finally propanamide by heating.

In conclusion, carboxylic acids are converted to amides in two steps.

Learn more about carboxylic acids and amides at: brainly.com/question/9616270

#SPJ1

8 0

2 years ago

Calculate the volume of a sample of gas at 5.75 atm if it occupies 5.14 L at 2.49 atm

Ksivusya [100]

Boyle's Law

Pressure 1 × Volume 1 = Pressure 2 × Volume2

or P1×V1= P2×V2

Finding Volume 2

(5.75atm)(5.14L) = (2.49atm)(V2)

Then Multiply

29.55atm•L = 2.49atm(V2)

Divided by 2.49

29.56atm•L / 2.49atm = 2.49atm(V2) / 2.49atm

V2= 11.87 L

4 0

3 years ago

What is the molality of a solution of Fe(ClO3), in water that freezes at -2.72°C?

Anon25 [30]

Answer:

0.366m = Molality of the solution

Explanation:

To solve this question we must know the addition of a solute produce decreasing in freezing point regard to the pure solvent. The equation is:

ΔT = m*Kf*i

<em>Where ΔT is change in freezing point </em>

(As freezing point of water is 0°C, the ΔT is 2.72°C)

<em>Kf is freezing point depression constant = 1.86°C/m for water</em>

<em>i is Van't Hoff factor. The number of ions produced when 1 mole of the salt is dissolved = 4 ions for Fe(ClO₃)₃, Fe³⁺ and 3 ClO₃⁻ ions</em>

<em>m is molality of the solution.</em>

<em />

Replacing:

2.72°C = m*1.86°C/m*4

<h3>0.366m = Molality of the solution</h3>

<em />

3 0

3 years ago

Copper(II) sulfate forms a bright blue hydrate with the formula CuSO 4 ⋅ n H 2 O ( s ) . If this hydrate is heated to a high eno

Arada [10]

Answer:

The value of n in the hydrate formula is 5 , $CuSO_4.5H_2O$ .

Explanation:

$CuSO_4.nH_2O\rightarrow CuSO_4+nH_2O$

Mass of hydrate of copper sulfate = 14.220 g

Moles of hydrate of copper sulfate = $\frac{14.220 g}{(159.5+n\times 18) g/mol}$

Mass of copper sulfate after heating = 8.9935 g

Moles of copper sulfate = $\frac{8.9935 g}{159.5 g/mol}$

$\frac{14.220 g}{(159.5+n\times 18) g/mol}=\frac{8.9935 g}{159.5 g/mol}$

Solving for n, we get:

n = 5

The value of n in the hydrate formula is 5 , $CuSO_4.5H_2O$ .

5 0

3 years ago

Nikolas, the fire extinguisher, and the skateboard have a combined mass of 50 kg. What force would the fire extinguisher have to

murzikaleks [220]

Answer:

Force used by fire extinguisher = 60 N

Explanation:

Given:

Mass of skateboard with fire extinguisher = 50 kg

Acceleration of fire extinguisher = 1.2 m/s²

Find:

Force used by fire extinguisher = ?

Computation:

⇒ Force = Mass × Acceleration

⇒ Force used by fire extinguisher = Mass of skateboard with fire extinguisher × Acceleration of fire extinguisher

⇒ Force used by fire extinguisher = 50 kg × 1.2 m/s²

⇒ Force used by fire extinguisher = 60 N

3 0

3 years ago

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