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OleMash [197]
3 years ago
11

An aqueous potassium chloride, KCl, solution is made by dissolving 0.295 0.295 mol KCl in 740.0 740.0 g of water. Calculate the

molality of the solution.
Chemistry
2 answers:
Pepsi [2]3 years ago
6 0

Answer:

Molality is 0.40 m

Explanation:

Molality is a sort of concentration that indicates the moles of solute dissolved in 1kg of solvent.

To determine molality we need the moles of solute, and the mass of solvent in kg so:

We convert the mass of solvent from g to kg:

740 g . 1kg/1000g = 0.740 kg

We know the moles, so we can determine molality

Molality (mol/kg) = 0.295 mol/ 0.740kg = 0.40 m

densk [106]3 years ago
5 0

Answer:

Molality of the solution = 0.399 molal

Explanation:

Step 1: Data given

Number of moles KCl = 0.295 moles

Mass of water = 740.0 grams

Step 2: Convert mass to kg

740 grams = 740 *10^-3 kg = 0.740 kg

Step 3: Calculate the molality of the solution

Molality of the solution = moles KCl / mass water

Molality of the solution = 0.295 moles / 0.740 kg

Molality of the solution = 0.399 mol /kg = 0.399 molal

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One mole of an ideal gas with a volume of 1.0 L and a pressure of 5.0 atm is allowed to expand isothermally into an evacuated bu
Deffense [45]

Answer:

w= - 1.7173 kJ, q= 1.7173 kJ, q(rev) = 1717.3 J = 1.7173 kJ.

Explanation:

Okay, from the question we are given the information below;

Number of moles, n= 1 mole; initial volume, v(1) = 1.0 litres (L); pressure (p) = 5atm, final volume(v2) = 2.0 Litres(L) ; the workdone, w= not given; the heat, q and q(rev)= not given and the gas was said to expand isothermally.

So, this question is a question from the part of chemistry known as thermodynamics. Therefore, grip yourself we are delving into thermodynamics 'waters' now.

For expansion isothermally; the workdone, w= -nRT ln v2/v1.

Where T= temperature= 25° C = 298 k and R= gas constant.

Therefore; workdone, w = - 1 × 8.314 × 298 × ln(2/1).

Workdone,w= - 1717.32204643. =

- 1717.3 Joules (J).

==> Workdone,w= - 1.7173 kJ.

Then, we are to find q. q can be solved by using the first law of thermodynamics, which by mathematical representation is:

∆U= q + w. Where ∆U= change in internal enegy. Since the question is dealing with isothermal expansion, there is this rule that says for an isothermal expansion ∆U = 0.

Hence, 0 =q + [- 1717.3 Joules (J)].

q=1717.3 J = 1.7173 kJ.

Finally, the q(rev) which is= nRT ln (v2/V1).

q(rev) = 1 × 8.314 × 298 ln (2/1).

q(rev) = 1717.3 J = 1.7173 kJ.

PS: please note the negative signs in the workdone and the positive sign in the q(rev).

7 0
3 years ago
Iron is extracted from iron oxide in the Blast Furnace: Fe 2 O 3 + 3 CO → 2 Fe + 3 CO 2
arsen [322]

a. mass of iron = 69.92 g

b. percent yield = 93%

<h3>Further eplanation </h3>

Percent yield is the compare of the amount of product obtained from a reaction with the amount you calculated

General formula:

Percent yield = (Actual yield / theoretical yield )x 100%

An actual yield is the amount of product actually produced by the reaction. A theoretical yield is the amount of product that you calculate from the reaction equation according to the product and reactant coefficients

a.

Reaction

Fe₂O₃+3CO⇒2Fe+3CO₂

MW Fe₂O₃ :  159.69 g/mol

mol Fe₂O₃

\tt \dfrac{100}{159,69}=0.626

mol Fe₂O₃ : mol Fe = 1 : 2

mol Fe :

\tt \dfrac{2}{1}\times 0.626=1.252

mass of Fe(Ar=55.845 g/mol) :

\tt 1.252\times 55.845=69.92~g

b.

actual yield = 65 g

theoretical yield = 69.92 g

percent yield :

\tt =\dfrac{65}{69.92}=0.93=93\%

8 0
3 years ago
Liquid octane CH3CH26CH3 will react with gaseous oxygen O2 to produce gaseous carbon dioxide CO2 and gaseous water H2O . Suppose
Slav-nsk [51]

Answer:

The minimum mass of octane that could be left over is 43.0 grams

Explanation:

Step 1: Data given

Mass of octane = 73.0 grams

Mass of oxygen = 105.0 grams

Molar mass octane = 114.23 g/mol

Molar mass oxygen = 32.0 g/mol

Step 2: The balanced equation

2C8H18 + 25O2 → 16CO2 + 18H2O

Step 3: Calculate the number of moles

Moles = mass / molar mass

Moles octane = 73.0 grams / 114.23 g/mol

Moles octane = 0.639 moles

Moles O2 = 105.0 grams / 32.0 g/mol

Moles O2 = 3.28 moles

Step 4: Calculate the limiting reactant

For 2 moles octane we need 25 moles O2 to produce 16 moles CO2 and 18 moles H2O

O2 is the limiting reactant. It will completely be consumed. (3.28 moles). There will react 3.28 / 12.5 = 0.2624 moles. There will remain 0.639 - 0.2624  = 0.3766 moles octane

Step 5: Calculate mass octane remaining

Mass octane = moles * molar mass

Mass octane = 0.3766 moles * 114.23 g/mol

Mass octane = 43.0 grams

The minimum mass of octane that could be left over is 43.0 grams

3 0
3 years ago
Explain the terms physical properties of metals Malleability and ductility, and how they used in daily life situation ?​
EastWind [94]

Answer:

Malleability means that metals can be hammered into sheets and foils. For example, aluminium foils are used for wrapping food stuffs, silver foils are used for decorative purposes on sweets and fruits. Ductility means that metals can be drawn into wires. Gold and silver wires are used in ornaments.

and For jewellery and ornaments, gold, platinum and silver are being used. For building purposes, iron and steel can be used. Iron and aluminium are used as utensils. The thermometer uses mercury and helps to monitor the temperature.

Explanation:

please rate as brainliest

7 0
1 year ago
Read 2 more answers
What is the number of protons of oxygen
Deffense [45]

Answer: I believe it's 8

Explanation: The oxygen atom has therefore 8 neutrons, 8 protons and 8 electrons.

8 0
3 years ago
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