Ionic compounds are solid at room temperature because they have

If you add 25.0 mL of water to 125 mL of a 0.150 M LiOH solution, what will be the molarity of the resulting diluted solution?

Alborosie

Concentration is the number of moles of solute in a fixed volume of solution

Concentration(c) = number of moles of solute(n) / volume of solution (v)

25.0 mL of water is added to 125 mL of a 0.150 M LiOH solution and solution becomes more diluted.

original solution molarity - 0.150 M

number of moles of LiOH in 1 L - 0.150 mol

number of LiOH moles in 0.125 L - 0.150 mol/ L x 0.125 L = 0.01875 mol

when 25.0 mL is added the number of moles of LiOH will remain constant but volume of the solution increases

new volume - 125 mL + 25 mL = 150 mL

therefore new molarity is

c = 0.01875 mol / 0.150 L = 0.125 M

answer is 0.125 M

7 0

3 years ago

If a sample of gas is located 10.2 cm from the injection point and the chart speed is 0.5 cm/min, what is the retention time?

Archy [21]

Answer : The retention time is, 20 min

Explanation :

Retention time : It is defined as the amount of time a compound spends on the column after it has been injected.

Formula of retention time is:

$\text{Retention time}=\frac{\text{Distance from injection point to center of peaks}}{\text{Chart recorded speed}}$

Given:

Distance from injection point to center of peaks = 10 cm

Chart recorded speed = 0.5 cm/min

Now put all the given values in the above formula, we get:

$\text{Retention time}=\frac{10cm}{0.5cm/min}$

Retention time = 20 min

Thus, the retention time is, 20 min

3 0

3 years ago

Which of the following is not a property of a buffer solution? a) It is a mixture of a weak acid and its conjugate base. b) Resi

m_a_m_a [10]

Answer:

e) pH is independent of concentration.

Explanation:

a) It is a mixture of a weak acid and its conjugate base. TRUE. A buffer is defined as a mixture of a weak acid and its conjugate base or a weak base and its conjugate acid.

b) Resists pH changes because it reacts with added acid or base. TRUE. Thermodynamically, the reaction of added acid or base is faster with the buffer mixture than with H⁺ or OH⁻ ions of the solutions.

c) The maximum buffer capacity is at pH = pKa. TRUE. The buffer capacity is pka±1. For this, buffer capacity is maximum in pka.

d) pH is dependent on the solution ionic strength and temperature. TRUE. Ionic strength and temperature are factors that influence concentrations of ions in solutions as the H⁺ ion that is the responsible

e) pH is independent of concentration. FALSE. pH in a buffer depends completely of concentrations of the acid and its conjugate base or vice versa.

I hope it helps!

8 0

3 years ago

Convert 78.9 kJ into calories (can you also explain how pls, ty <3)

Katena32 [7]

Answer:

18857

Explanation:

1j=0.239cal

78.9kj=78900j

78.9kj= 78900×0.239=18857cal

4 0

3 years ago

50.0 g of copper was dropped into 250.0mL of H2O at 25.0°C in a coffee cup calorimeter. The copper and H2O reached thermal equil

siniylev [52]

Answer:

Initial temperature of copper = 163.3 °C

Explanation:

Specific heat capacity:

It is the amount of heat required to raise the temperature of one gram of substance by one degree.

Formula:

Q = m.c. ΔT

Q = amount of heat absorbed or released

m = mass of given substance

c = specific heat capacity of substance

ΔT = change in temperature

ΔT = final temperature - initial temperature

Given data:

Mass of copper = 50 g

Initial temperature of copper = ?

Final temperature = 27.5°C

Initial temperature of water = 25.0°C

Specific heat capacity of copper = 0.385 j/g.°C

Specific heat capacity of water = 4.184 J/g°C

Volume of water = 250.0 mL or 250.0 g

Solution:

Formula:

- Qm = +Qw

Now we will put the values in formula.

-50 g × 0.385 j/g.°C × [ 27.5°C -x] = 250 g × 4.184 J/g°C × [ 27.5°C - 25.0°C]

-50 g × 0.385 j/g.°C × [ 27.5°C -x] = 250 g × 4.184 J/g°C × 2.5°C

-19.25 j/°C × [ 27.5°C -x] = 2615 j

27.5°C -x = 2615 j / -19.25 j/°C

27.5°C -x = -135.8°C

x = 27.5°C + 135.8°C

x = 163.3 °C

7 0

3 years ago