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3 years ago

Which material is a pure substance?

2 answers:

8 0

The answer is B. The material that can be considered as a pure substance is the compound. A pure substance is defined as a material that is only composed of one substance. The other choices given are mixtures where there are two or more different substances in a material.

Natasha2012 [34]3 years ago

6 0

<u>B) compound</u> is a pure substance

Further explanation

A pure substance can be an element or compound.

The element is a single substance that cannot be broken down anymore or the simplest substance.

While the compound is a pure substance that is formed from a combination of two or more elements through chemical reactions and has a constant chemical ratio.

A mixture is a combination of two or more single substances. The properties of the mixture component are not lost / unchanged as in compounds.

The mixture can be divided into a homogeneous mixture if the composition / ratio of each substance in the mixture is the same and heterogeneous mixture if the ratio of the composition of the substances is not the same (can be varied) in each place.

Mixtures can also be divided into solutions, suspensions and colloids based mainly on the size of the particles

A) alloy

alloy is a mixture of elements that have metal properties

B) compound

Compounds are represented in chemical formulas which can be separated into their constituent elements by chemical processes

C) mixture

can be separated by physical or mechanical means, the composition can be changed depending on the proportion of pure substances that form it

D) solution

Solution is: a mixture of two or more substances consisting of a solute and a solvent. The particle size of the solution is very small, less than 1 nm.

<h3>Learn more </h3>

A heterogeneous mixture

brainly.com/question/5428813

a homogeneous mixture

brainly.com/question/1799869

an example of a physical change

brainly.com/question/1119909

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Which of the following are second-order reactions? a. C2H6 → 2 CH3 b. 2 N2O5 → 4 NO2 + O2 c. 2 HI → H2 + I2 d. 2 N2O → 2 N2 + O2

Klio2033 [76]

Answer:

The answer is b, c, d, e

Explanation:

b. 2 N2O5 → 4 NO2 + O2

r = k [N2O5]^2 --> Second-order regarding global reaction

c. 2 HI → H2 + I2

r = k [HI]^2 --> Second-order regarding global reaction

d. 2 N2O → 2 N2 + O2

r = k [N2O]^2 --> Second-order regarding global reaction

e. 2 NO2 → 2 NO + O2

r = k [NO2]^2 --> Second-order regarding global reaction

8 0

2 years ago

A 25.0 ml sample of 0.723 m hclo4 is titrated with a 0.27303 m koh solution. the h3o+ concentration after the addition of 66.2 m

tia_tia [17]

This doesn't need an ICE chart. Both will fully dissociate in water.

Assume HClO4 and KOH reacts with one another. All you need to do is determine how much HClO4 will remain after the reaction. Calculate pH.

Step 1:

write out balanced equation for the reaction

HClO4+KOH ⇔ KClO4 + H2O

the ratio of HClO4 to KOH is going to be 1:1. Each mole of KOH we add will fully react with 1 mole of HClO4

Step 2:

Determining the number of moles present in HClO4 and KOH

Use the molar concentration and the volume for each:
25 mL of 0.723 M HClO4

Covert volume from mL into L:
25 mL * 1L/1000mL = 0.025 L

Remember:

M = moles/L so we have 0.025 L of 0.723 moles/L HClO4

Multiply the volume in L by the molar concentration to get:

0.025L x 0.723mol/L = 0.0181 moles HClO4.

Add 66.2 mL KOH with conc.=0.273M
66.2mL*1L/1000mL = .0662 L
.0662L x 0.273mol/L = 0.0181 moles KOH

Step 3:

Determine how much HClO4 remains after reacting with the KOH.

Since both reactants fully dissociate and are used in a 1:1 ratio, we just subtract the number of moles of KOH from the number of moles of HClO4:

moles HClO4 = 0.0181; moles KOH = 0.0181, so 0.0181-0.0181 = 0

This means all of the HClO4 is used up in the reaction.

If all of the acid is fully reacted with the base, the pH will be neutral = 7.

Determine the H3O+ concentration:

pH = -log[H3O+]; [H3O+] = 10-pH = 10-7

The correct answer is 1.0x10-7.

3 0

3 years ago

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What chemical change is magnetizing steel

labwork [276]

Magnetizing steel is a physical change, not a chemical change.

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3 years ago

How much time would it take to distribute one avagadro's number of wheat grains if 10^10 grains are A)1.9*10^2 years B)1.9*10^10

Makovka662 [10]

Answer:

It takes 1.9 $\times 10^{6}$ years to distribute all the grains.