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3 years ago

Molarity.

1 answer:

7 0

<span>Find if the same solution would be equal:
=> 0.5 grams of Sodium chloride dissolved in 0.05 liters solution
=> 0.5 moles of sodium chloride dissolved in 0.05 liters solution
The answer is NO. They are not equal because 0.5 grams of sodium chloride is equivalent to 10 moles of sodium chloride which makes 0.5 grams of sodium chloride mixed with 0.05 liters of solution more concentrated than 0.5 moles of sodium chloride dissolved in 0.05 liters of solution.

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How is the hardness range for a mineral determined?

Setler79 [48]

As common sense dictates, Mohs Scale is based on the fact that a harder material will scratch a softer one. By using a simple scratch test, you can determine the relative hardness of an unknown mineral.

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3 years ago

The diagram below shows the layers in Earth's interior.

Arada [10]

Answer:

layer B is liquid because of the inner members and layer A is solid because of the outer members

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2 years ago

Question 1(Multiple Choice Worth 3 points)

Bingel [31]

1) Answer:

moles of oxygen (n) = 1.86 moles

Explanation:

according to Boyle's law the formula to solve this problem is:

PV=nRt

when P is the pressure which equal 1.25 atm

and V is the volume which equal 37.5 L

n is the number of moles which we need to calculate it

R is constant which equal 0.082

t is the temperature in kelvin

By substitution:

1.25*37.5 = n * 0.082 * 307

So n = 1.86 moles

2) Answer:

the volume of oxygen gas = 34 L

Explanation:

at standard temperature and pressure (STP) 1 mole of gas will equal = 22.4L

So when we have 1.5 moles of oxygen at standard temperature and pressure (STP) so we will estimate it like that

1.5 moles *22.4 L/ 1 mole = approximately 34 L

3) Answer:

The volume of H2 = 2.29 L

Explanation:

according to the Balanced equation we can see that the molar ratio between Zn and H2 1 : 1

so to know the number of moles of H2 we will get it for Zn first :

number of moles Zn = mass of Zn / molar mass Zn

= 5.98 / 65.39 =0.0914 moles

so number of moles H2 = 0.09 moles

by substitution in the following formula:

PV = nRT

0.978 * V = 0.09 * 0.082 * 298

so The volume of H2 = 2.29 L

4) Answer:

Volume of O2 = 1.4 L

Explanation:

first we have to balance the equation:

2Na2O2 +2CO2 → 2Na2CO3 + O2

2 mole CO2 give 1 mole of O2 so the molar ratio is 2:1

at STP 1 mole of gas will equal = 22.4 L

??? moles of CO2 = 2.8

n CO2 = 0.125 moles so n O2 = 0.125 /2 = 0.0625 moles

so when 1 mole of as = 22.4

0.0625 moles O2 = ???

Volume of O2 =0.0625 moles * 22.4 L/ 1 mole

= 1.4 L

5) Answer:

the initial quantity of sodium metal used = 17.2 gram

Explanation:

at STP 1 mole of gas will equal = 22.4 L

so moles of H2 equal ?? when 8.40 liters of H2 gas were produced

so moles of H2 = 8.4/22.4 =0.375 moles

and according to the balanced equation the molar ratio between H2 ans Na is 1 : 2

so number of moles for Na = 0.375 *2 = 0.75 moles

to get the initial quantity of sodium metal (mass Na) = number of moles * molar mass

mass Na = 0.75 moles * 23 gm/mole= 17.25

6) Answer:

False

Explanation:

because STP means standard temperature and pressure. and the Standard temperature must be 273 K and the standard pressure must be 1 atm but in the question the temperature is 298 K not 273 K so , It is not a standard temperature

7) Answer:

22.4 liters

Explanation:

1 mole of gas will equal = 22.4 L

because at the Standard temperature must be 273 K and the standard pressure must be 1 atm

so V = nRT/P

=1 mole * 0.082 * 273 K / 1 aTm

= 22.4 liters

4 0

4 years ago

Which molecular solid would have the highest melting point?

TEA [102]

Answer:

Choice B. The solid with hydrogen bonding.

Assumption: the molecules in the four choices are of similar sizes.

Explanation:

Molecules in a molecular solid are held intact with intermolecular forces. To melt the solid, it is necessary to overcome these forces. The stronger the intermolecular forces, the more energy will be required to overcome these attractions and melt the solid. That corresponds to a high melting point.

For molecules of similar sizes,

The strength of hydrogen bonding will be stronger than the strength of dipole-dipole attractions.
The strength of dipole-dipole attractions (also known as permanent dipole) will be stronger than the strength of the induced dipole attractions (also known as London Dispersion Forces.)

That is:

Strength of Hydrogen bond > Strength of Dipole-dipole attractions > Strength of Induced dipole attractions.

Accordingly,

Melting point due to Hydrogen bond > Melting point due to Dipole-dipole attractions > Melting point due to Induced Dipole attractions.

Induced dipole is possible between all molecules.
Dipole-dipole force is possible only between polar molecules.
Hydrogen bonds are possible only in molecules that contain $\rm H$ atoms that are bonded directly to atoms of $\rm F$ , $\rm O$ , or $\rm N$ .

As a result, induced dipoles are the only force possible between molecules of the solid in choice C. Assume that the molecules are of similar sizes, such that the strengths of induced dipole are similar for these molecules.

Melting point in choice B > Melting point in choice D > Melting point in choice A and C.

8 0

3 years ago

How can the chemical properties of an element help determine the types of materials it can form?

AleksandrR [38]

<h2><u>Answer:</u></h2>

The quantity of protons likewise decides the character of the component. Electrons have a negative charge. The furthest or valence electrons of a particle are the ones that partake in synthetic responses. A component's substance properties rely upon its valence electrons.

The general properties of issue, for example, shading, thickness, hardness, are instances of physical properties. Properties that portray how a substance changes into a totally extraordinary substance are called synthetic properties. Combustibility and consumption/oxidation obstruction are instances of compound properties.

Reactivity with other chemicals.

Toxicity.

Coordination number.

Flammability.

Enthalpy of formation.

Heat of combustion.

Oxidation states.

Chemical stability

5 0

3 years ago