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4 years ago

Which statement best describes plastics?

Chemistry

2 answers:

Ann [662]4 years ago

5 0

Answer: Option (A) is the correct answer.

Explanation:

Plastics are basically organic polymers and it is known that polymers are long chain molecules.

Whereas when large number of monomer units combine together then it results in the formation of a polymer.

Plastics are able to change their shape and burn easily when come in contact of fire along with emission of harmful gases.

Therefore, we can conclude that the statement plastics are large organic molecules called Polymers, is true.

Dmitry_Shevchenko [17]4 years ago

4 0

I think the correct answer is C

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What type of change does electron have?

Valentin [98]

Proton—positive; electron—negative; neutron—no charge. The charge on the proton and electron are the same size but opposite. The same number of protons and electrons exactly cancel one another in a neutral atom.

7 0

3 years ago

Read 2 more answers

Determine the volume of distilled water that should be added to 20.0 mL of 12.0 M HCl(aq) in order to prepare a 0.500 M HCl(aq)

BARSIC [14]

Answer:

$V_{H_2O}=460 mL$

Explanation:

Hello!

In this case, in a dilution process, water is added to a solute in order to decrease its concentration but increase the volume of the solution. It means that if we have 20.0 mL of a 12.0-M solution of HCl and we want a 0.500-M solution, we need to apply the following formula considering that the moles remain unchanged:

$M_1V_1=M_2V_2$

Thus, solving for the final volume is:

$V_2=\frac{M_1V_1}{M_2}$

So plugging in the values we obtain:

$V_2=\frac{12.0M*20.0mL}{0.500M}\\\\V_2=480 mL$

Now, since the initial volume of acid was 20.0 mL and the final volume is 480 mL, the added volume of distilled water is:

$V_{H_2O}=480-20=460 mL$

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3 years ago

Enter your answer in the box provided. How many grams of helium must be added to a balloon containing 6.24 g helium gas to doubl

Archy [21]

Answer : The mass of helium gas added must be 12.48 grams.

Explanation : Given,

Mass of helium (He) gas = 6.24 g

Molar mass of helium = 4 g/mole

First we have to calculate the moles of helium gas.

$\text{Moles of }He=\frac{\text{Mass of }He}{\text{Molar mass of }He}=\frac{6.24g}{4g/mole}=1.56moles$

Now we have to calculate the moles of helium gas at doubled volume.

According to the Avogadro's law, the volume of gas is directly proportional to the number of moles of gas at same pressure and temperature. That means,

$V\propto n$

or,

$\frac{V_1}{V_2}=\frac{n_1}{n_2}$

where,

$V_1$ = initial volume of gas = V

$V_2$ = final volume of gas = 2V

$n_1$ = initial moles of gas = 1.56 mole

$n_2$ = final moles of gas = ?

Now we put all the given values in this formula, we get

$\frac{V}{2V}=\frac{1.56mole}{n_2}$

$n_2=3.12mole$

Now we have to calculate the mass of helium gas at doubled volume.

$\text{Mass of }He=\text{Moles of }He\times \text{Molar mass of }He$

$\text{Mass of }He=3.12mole\times 4g/mole=12.48g$

Therefore, the mass of helium gas added must be 12.48 grams.

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3 years ago

Describe the error (what rule does it violate) if there is one in each of the following:

Free_Kalibri [48]

Answer:

prolly the gay one

Explanation:

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3 years ago

38. A sample of calcium chloride, CaCl2, has a mass of 27.8 g (ref: p.330-340)

MAXImum [283]

Answer:

Explanation:

Given parameters:

Mass of CaCl₂ = 27.8g

Unknown:

Number of CaCl₂ in the compound = ?

Number of Cl⁻ ions in the compound = ?

Solution:

Problem 1:

The mole is the quantitative unit of measuring particles. The mole is defined as the amount of substance. It is usually expressed as:

Number of moles = $\frac{mass}{molar mass}$ (1)

To find the number of moles of CaCl₂, we have been given the mass of CaCl₂ but we don't know the molar mass of the compound yet.

Find the molar mass of CaCl₂ given that atomic mass of Ca is 40g/mol and atomic mass of Cl is 35.5g/mol

Molar mass of CaCl₂ = 40 + 2(35.5) = 111g/mol

Since mass of CaCl₂ is 27.8g, we then substitute in the equation (1):

Number of moles = $\frac{27.8}{111}$ = 0.2505mole

Problem 2:

To find the number of chloride ions present in the compound, we must express the compound in its ionic form:

CaCl₂ ⇄ Ca²⁺ + 2Cl⁻

This is the ionic form of the compound when in aqueous solutions.

In this kind of problem, we solve from the specie with the known parameters. Here, we know the number of moles of CaCl₂. We can use it determine the number of Chloride ions.

From the ionic form, we see that:

1 mole of the known CaCl₂ produced 2 moles of the unknown Cl⁻

0.2505 mole of CaCl₂ will produce (2 x 0.2505)moles of Cl⁻

This gives, 0.5009 mole of Cl⁻ ions in the CaCl₂ compound.

Note: 1 mole of a substance gives 6.02 x 10²³particles

0.5009mole of Cl⁻ will produce 0.5009 x 6.02 x 10²³;

= 3.02 x 10²³ chloride ions are present

8 0

3 years ago