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3 years ago

How many moles are in 25.3 g of a sample of potassium nitrate (KNO3)?

Chemistry

1 answer:

aksik [14]3 years ago

8 0

Answer:

25.3 g of KNO₃ contain 0.25 moles.

Explanation:

Given data:

Number of moles of KNO₃ = ?

Mass of KNO₃ = 25.3 g

Solution:

Formula:

Number of moles = mass/ molar mass

Molar mass of KNO₃:

KNO₃ = 39 + 14+ 16×3

KNO₃ = 101 g/mol

Now we will put the values in formula.

Number of moles = 25.3 g/ 101 g/mol

Number of moles = 0.25 mol

Thus, 25.3 g of KNO₃ contain 0.25 moles.

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A liquid solvent is added to a flask containing an insoluble solid. The total volume of the solid and liquid together is 80.0 mL

Lyrx [107]

Answer:

111.44 g

Explanation:

We'll begin by calculating the volume of the solvent. This can be obtained as follow:

Mass of solvent = 21 g

Density of solvent = 0.865 g/mL.

Volume of solvent =?

Density = mass /volume

0.865 = 21 /volume of solvent

Cross multiply

0.865 × volume of solvent = 21

Divide both side by 0.865

Volume of solvent = 21 / 0.865

Volume of solvent = 24.28 mL

Next, we shall determine the volume of the solid. This can be obtained as follow:

Volume of solvent + solid = 80.0 mL.

Volume of solvent = 24.28 mL

Volume of solid =?

Volume of solid = (Volume of solvent + solid) – (Volume of solvent)

Volume of solid = 80 – 24.28

Volume of solid = 55.72 mL

Finally, we shall determine the mass of the solid. This can be obtained as follow:

Density of solid = 2.00 g/mL.

Volume of solid = 55.72 mL

Mass of solid =.?

Density = mass / volume

2 = mass of solid / 55.72

Cross multiply

Mass of solid = 2 × 55.72

Mass of solid = 111.44 g

Therefore, the mass of the solid is 111.44 g

8 0

3 years ago

The combustion of 0.570 g of benzoic acid (ΔHcomb = 3,228 kJ/mol; MW = 122.12 g/mol) in a bomb calorimeter increased the tempera

torisob [31]

Answer:

The temperature change from the combustion of the glucose is 6.097°C.

Explanation:

Benzoic acid;

Enthaply of combustion of benzoic acid = 3,228 kJ/mol

Mass of benzoic acid = 0.570 g

Moles of benzoic acid = $\frac{0.570 g}{122.12 g/mol}=0.004667 mol$

Energy released by 0.004667 moles of benzoic acid on combustion:

$Q=3,228 kJ/mol \times 0.004667 mol=15.0668 kJ=15,066.8 J$

Heat capacity of the calorimeter = C

Change in temperature of the calorimeter = ΔT = 2.053°C

$Q=C\times \Delta T$

$15,066.8 J=C\times 2.053^oC$

$C=7,338.92 J/^oC$

Glucose:

Enthaply of combustion of glucose= 2,780 kJ/mol.

Mass of glucose=2.900 g

Moles of glucose = $\frac{2.900 g}{180.16 g/mol}=0.016097 mol$

Energy released by the 0.016097 moles of calorimeter combustion:

$Q'=2,780 kJ/mol \times 0.016097 mol=44.7491 kJ=44,749.1 J$

Heat capacity of the calorimeter = C (calculated above)

Change in temperature of the calorimeter on combustion of glucose = ΔT'

$Q'=C\times \Delta T'$

$44,749.1 J=7,338.92 J/^oC\times \Delta T'$

$\Delta T'=6.097^oC$

The temperature change from the combustion of the glucose is 6.097°C.

6 0

3 years ago

After fertilization, female cones become very:<br> sticky<br> light<br> O hard

S_A_V [24]

Answer:

light

Explanation:

sorry don't now this one

8 0

3 years ago

A mixture of0.161 moles of C is reacted with 0.117 moles of O2 in a sealed, 10.0 L-vessel at 500.0 K, producing a mixture of CO

labwork [276]

Answer:

number of moles of CO2 is 0.054

number of moles of CO is 0.107

number of moles of O2 remaining is 0.01 mole

mole fraction of CO is 0.63

Explanation:

Firstly, we write the equation of reaction;

3C(s) +2O2(g) → CO2(g) +2CO(g)

Now, we proceed.

From the written equation, we can deduce that

3 mol C = 2 mol O2 = 1 mol CO2 = 2 mol CO

No of mol of C reacted = 0.161 mol

limiting reactant according to the question is Carbon

a. no of mol of CO2 formed = 0.161*1/3 = 0.054 moles ( no of moles of CO2 formed is one-third of no of moles of carbon reacted. This is obtainable from their mole ratio 1:3)

b. no of mol of CO formed = 0.161*2/3 = 0.107 mol

c. no of mol of O2 remaining = 0.117 - (0.151*2/3) = 0.117-0.107 = 0.01 mole

d. mole fraction of CO = no of mol of CO/Total number of moles

= 0.107/(0.107+0.054+0.01)

= 0.625730994152 which is approximately 0.63

5 0

3 years ago

Can you help me out plz and thank u

Nonamiya [84]

Answer:

stirring

Explanation:

when you stir it spreads the item out more to be fully covered and dissolve faster. like putting sugar in tea, if you don' t stir it wont dissolve fast

5 0

3 years ago