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asambeis [7]
3 years ago
12

1). If the molarity of a KCl (potassium chloride) solution is 8.0 M, which of these is true?

Chemistry
1 answer:
Olin [163]3 years ago
8 0

Q. No. 1 is Incomplete.

___________________________________________

Q. No.2: A saline solution contains 0.015 mol NaCl in exactly 0.10 L of solution. What is the molarity of the solution?

Answer:

                  Molarity  =  0.15 mol.L⁻¹ (or) 0.15 M

Solution:

                    Molarity is the the unit of concentration and it is expressed as the amount of solute dissolved per unit volume of solution. It is expressed as,

                        Molarity  =  Moles / Volume of Solution  (1)

Data Given;

                        Moles  =  0.015 mol

                        Volume  =  0.10 L

Now, putting value of Moles and Volume in eq. 1,

                        Molarity  =  0.015 mol ÷ 0.10 L

                        Molarity  =  0.15 mol.L⁻¹ (or) 0.15 M

___________________________________________

Q. No.3: A solution is prepared by dissolving 42.23 g of NH₄Cl into enough water to make 0.500 L of solution. Calculate its molarity.

Answer:

                  Molarity  =  1.578 mol.L⁻¹ (or) 1.578 M

Solution:

Data Given;

                 Mass  =  42.23 g

                 Volume  =  0.50 L

                 M.Mass of NH₄Cl  =  53.49 g/mol

First calculate Moles for given mass as,

                  Moles  =  Mass / M.mass

                  Moles  =  42.23 g / 53.49 g.mol⁻¹

                  Moles  =  0.789 mol

Formula used,

                   Molarity  =  Moles / Vol. of Solution  ---- (1)

Now, putting value of Moles and Volume in eq. 1,

                   Molarity  =  0.789 mol ÷ 0.50 L

                   Molarity  =  1.578 mol.L⁻¹ (or) 1.578 M

___________________________________________

Q. No.4: Determine the concentration of a solution made by dissolving 10.0 g of sodium chloride (NaCl) in 0.75 L of solution.

Answer:

                  Molarity  =  0.228 mol.L⁻¹ (or) 0.228 M

Solution:

Data Given;

                 Mass  =  10.0 g

                 Volume  =  0.75 L

                 M.Mass of NaCl  =  58.44 g/mol

First calculate Moles for given mass as,

                  Moles  =  Mass / M.mass

                  Moles  =  10.0 g / 58.44 g.mol⁻¹

                  Moles  =  0.171 mol

Formula used,

                   Molarity  =  Moles / Vol. of Solution  ---- (1)

Now, putting value of Moles and Volume in eq. 1,

                   Molarity  =  0.171 mol ÷ 0.75 L

                   Molarity  =  0.228 mol.L⁻¹ (or) 0.228 M

___________________________________________

Q. No.5: Determine the concentration of a solution made by dissolving 44.0 g of calcium chloride (CaCl₂) in 0.30 L of solution.

Answer:

                  Molarity  =  1.32 mol.L⁻¹ (or) 1.32 M

Solution:

Data Given;

                 Mass  =  44.0 g

                 Volume  =  0.30 L

                 M.Mass of CaCl₂  =  110.98 g/mol

First calculate Moles for given mass as,

                  Moles  =  Mass / M.mass

                  Moles  =  44.0 g / 110.98 g.mol⁻¹

                  Moles  =  0.396 mol

Formula used,

                   Molarity  =  Moles / Vol. of Solution  ---- (1)

Now, putting value of Moles and Volume in eq. 1,

                   Molarity  =  0.396 mol ÷ 0.30 L

                   Molarity  =  1.32 mol.L⁻¹ (or) 1.32 M

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What volume of oxygen (in L) is produced
sveticcg [70]

Answer:

12.36 L.

Explanation:

We'll begin by calculating the number of mole in 147.1 g of lead(II) nitrate, Pb(NO₃)₂. This can be obtained as follow:

Molar mass of Pb(NO₃)₂ = 207.2 + 2[14.01 + (16×3)]

= 207.2 + 2[14.01 + 48]

= 207.2 + 2[62.01]

= 207.2 + 124.02

= 331.22 g/mol

Mass of Pb(NO₃)₂ = 147.1 g

Mole of Pb(NO₃)₂ =?

Mole = mass / Molar mass

Mole of Pb(NO₃)₂ = 147.1 / 331.22

Mole of Pb(NO₃)₂ = 1.104 moles.

Next, we shall determine the number of mole of oxygen gas, O₂, produce from the reaction. This can be obtained as follow:

2Pb(NO₃)₂ —> 2PbO + 4NO₂ + O₂

From the balanced equation above,

2 moles of Pb(NO₃)₂ decomposed to produce 1 mole of O₂.

Therefore, 1.104 moles of Pb(NO₃)₂ will decompose to produce = (1.104 × 1)/2 = 0.552 mole of O₂.

Finally, we shall determine the volume occupied by 0.552 mole of oxygen gas, O₂. This can be obtained as follow:

1 mole of O₂ occupied 22.4 L at STP.

Therefore, 0.552 mole of O₂ will occupy = 0.552 × 22.4 = 12.36 L at STP.

Thus, the volume of oxygen gas, O₂ produced is 12.36 L.

6 0
3 years ago
1 message Which process results in the increase in entropy of the universe? the cooling of a hot cup of coffee in room temperatu
andreyandreev [35.5K]

Answer:

Melting of snow

Evaporation of water from desk

Explanation:

Processes that increase the entropy of the universe are those processes that have an increased disorderliness. We should note that there are three principal states of matter which are the liquid, gas and solid. The gaseous state is the most disorderly while the solid is the least disorderly.

Now. We can see that the cooling of a hot cup of coffee is a process that needs or leads to a loss in temperature which obviously decreases disorderliness of the universe.

The melting of snow however is a process that leads to an increase in the disorderliness of the universe. It entails moving from the solid state to the liquid state. It tends to move to a more disordered state indicating an increase in the entropy of the universe.

The evaporation of water from the desk is quite similar to that above. Hence since we are moving from the liquid to the gaseous state via evaporation, we can state that the entropy of the universe has increased since we have moved from a state with a lesser degree of disorderliness to a state that is more disordered I.e from liquid to gaseous state.

3 0
3 years ago
Write the balanced
lisabon 2012 [21]
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4 0
3 years ago
A chemical change occurs when
trasher [3.6K]

Answer:

Chemical changes occur when bonds are broken and/or formed between molecules or atoms. This means that one substance with a certain set of properties (such as melting point, color, taste, etc) is turned into a different substance with different properties

Explanation:

6 0
3 years ago
assuming the magnesium ribbon wasn't sufficiently polished to remove a coating of magnesium oxie on the surface. how would this
Ira Lisetskai [31]

The magnesium ribbon wasn't sufficiently polished to remove a coating of magnesium oxie on the surface. how would this affect the volume of hydrogen gas produced? would this error cause the gas constant to be overestimated, underestimated, or remain unaffected?

1. Since, the magnesium ribbon wasn’t sufficiently polished to remove a coating of magnesium oxide on surface, the actual mass of magnesium taken will be less (as it also contains magnesium oxide). Hence, the number of moles of magnesium reacted and the number of moles of hydrogen produced will be less.  Due to this, the volume of hydrogen gas produced will be less and the gas constant will be underestimated. R=\frac {PV}{nT} . Here n is calculated from weight of Mg taken but V is measured. Thus values of n will be same but the value of V will be lower. Hence, the value of R will be lower.

2. When droplets of water are remaining in the eudiometer tube, there volume will be added to the volume of hydrogen and the measured volume of hydrogen will be more than actual volume. Due to this, the value of the gas constant will be overestimated.

3. When small amount of hydrogen dissolves in water, the measured volume of hydrogen will be lower than the actual volume. This will underestimate the value of the gas constant.

4. When the temperature of the gas was underestimated, the value of the gas constant will be overestimated as the gas constant is inversely proportional to the temperature.            {PV}

                                                           R=

                                                                   {nT}.

Magnesium is a chemical detail with the symbol Mg and atomic number 12. it is a glittery gray solid which stocks many bodily and chemical residences with the alternative 5 alkaline earth metals (institution 2 of the periodic desk).

This element is produced in huge, growing old stars from the sequential addition of three helium nuclei to a carbon nucleus. whilst such stars explode as supernovas, a lot of the magnesium is expelled into the interstellar medium wherein it may recycle into new big name structures. Magnesium is the eighth maximum abundant element inside the Earth's crust and the fourth maximum not unusual detail in the Earth (after iron, oxygen and silicon), making up 13% of the planet's mass and a big fraction of the planet's mantle. it's miles the 0.33 maximum abundant detail dissolved in seawater, after sodium and chlorine.

Learn more about Magnesium here:-brainly.com/question/25860912

#SPJ4

8 0
1 year ago
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