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Determine the concentration of a solution made by dissolving 1.40grams NaCL in enough water to make 30.0mL of solution.

KiRa [710]

Answer: 0.8M

Explanation:

Given that,

Amount of moles of NaCl (n) = ?

Mass of NaCl in grams = 1.40 g

For molar mass of NaCl, use the molar masses:

Sodium, Na = 23g;

Chlorine, Cl = 35.5g

NaCl = (23g + 35.5g)

= 58.5g/mol

Since, amount of moles = mass in grams / molar mass

n = 1.40g / 58.5g/mol

n = 0.024 mole

Now, given that:

Amount of moles of NaCl (n) = 0.024

Volume of NaCl solution (v) = 30.0mL

[Convert 30.0mL to liters

If 1000 mL = 1L

30.0mL = 30.0/1000 = 0.03L]

Concentration of NaCl solution (c) = ?

Since concentration (c) is obtained by dividing the amount of solute dissolved by the volume of solvent, hence

c = n / v

c = 0.024 mole / 0.03 L

c = 0.8 M (0.8M means concentration is in moles per litres)

Thus, the concentration of the solution is 0.8M

3 0

3 years ago

A materials scientist has created an alloy containing aluminum, copper, and zinc, and wants to determine the percent composition

liubo4ka [24]

Answer:

0.8749 grams of hydrogen gas was formed from the reaction.

Explanation:

P = Pressure of hydrogen gad= 744 Torr = 0.98 atm

(1 atm = 760 Torr)

V = Volume of hydrogen gas= 11 L

n = number of moles of hydrogen gas= ?

R = Gas constant = 0.0821 L.atm/mol.K

T = Temperature of vapor = 27.0 °C = 300.15 K

Putting values in above equation, we get:

Using an ideal gas equation:

$PV=nRT$

$n=\frac{PV}{RT}=\frac{0.98 atm\times 11 L}{0.0821 L atm/mol K\times 300.15 K}$

n = 0.4374 moles

Mass of 0.4374 moles of hydrogen gas:

0.4374 mol × 2 g/mol = 0.8749 g

0.8749 grams of hydrogen gas was formed from the reaction.

7 0

4 years ago

What chemical change is magnetizing steel

labwork [276]

Magnetizing steel is a physical change, not a chemical change.

4 0

3 years ago

What is the freezing point of a solution of 498mL of water (solute) dissolved in 2.50 L of ethanol (solvent), C2H5OH? The densit

jok3333 [9.3K]

Answer:

Freezing T° of solution is -142.4°C

Explanation:

This excersise is about colligative properties, in this case freezing point depression,

ΔT = Kf . m . i

Where ΔT = Freezing T° of solvent - Freezing T° of solution

Kf = Cryoscopic constant

m = mol/kg (molality)

i = Number of ions dissolved.

Water is not ionic, so i = 1

Let's find out m.

We determine mass of water, by density

498ml . 1 g/mL = 498 g

We convert the mass of water to moles → 498 g . 1mol/18g = 27.6 moles

We determine mass of solvent by density

2500 mL . 0.789 g/mL = 1972.5 g

Notice, we had to convert L to mL to cancel units.

1 cm³ = 1 mL

We convert the mass from g to kg → 1972.5 g . 1kg /1000g = 1.97kg

We determine m = mol/kg → 27.6mol / 1.97kg = 13.9 m

Kf for ethanol is: 1.99 °C/m

Freezing T° for ethanol is: -114.6°C

We replace at formula: - 114.6°C - Freezing T° solution = 1.99 °C/m . 13.9 m . 1

- 114.6°C - Freezing T° solution = 27.8 °C

- Freezing T° solution = 27.8°C + 114.6°C

Freezing T° Solution = - 142.4 °C

7 0

3 years ago

Thallium consists of 29.5%TI-203 and 70.5%TI-205. What is the relative atomic mass of thallium

Galina-37 [17]

To determine the relative atomic mass of thallium, we multiply the molar mass of the isotopes to their corresponding relative abundance. The molecular percentages should sum up to 1. In this case, we multiply 203 by 0.295 and 205 by 0.705 and add the answers of the two. The final atomic mass is 204.41 g/mol.

3 0

3 years ago