Calculate the weight of solid NaOH required to prepare (a) 5 liters of a 2 M solution, (b) 2 liters of a solution of pH 11.5? i need full solution not just result please

A. 400g of NaOH.

B. 0.253g of NaOH.

Explanation:

A. The following data were obtained from the question:

Volume = 5 L

Molarity = 2 M

Mass =..?

Next, we shall determine the number of mole of NaOH. This can be obtain as follow:

Molarity = mole /Volume

2 = mole/5

Cross multiply

Mole = 2 x 5

Mole of NaOH = 10 moles

Finally, we shall convert 10 moles of NaOH to grams. This is illustrated below:

Mole of NaOH = 10 moles

Molar mass of NaOH = 23 + 16 + 1 = 40g/mol

Mass of NaOH =?

Mole = mass /molar mass

10 = mass of NaOH /40

Cross multiply

Mass of NaOH = 10 x 40

Mass of NaOH = 400g

Therefore, 400g of NaOH is needed to prepare the solution.

B. The following data were obtained from the question:

pH = 11.5

Volume = 2 L

Next, we shall determine the pOH of the solution. This can be obtain as shown below:

pH + pOH = 14

pH = 11.5

11.5 + pOH = 14

Collect like terms

pOH = 14 – 11.5

pOH = 2.5

Next, we shall determine the concentration of the hydroxide ion, [OH-] in the solution.

This is illustrated below:

pOH = - Log [OH-]

pOH = 2.5

2.5 = - Log [OH-]

-2.5 = Log [OH-]

Take the antilog of both side

[OH-] = antilog (-2.5)

[OH-] = 3.16×10¯³ M

Next, we shall determine the concentration of NaOH. This is illustrated below:

NaOH —> Na+ + OH-

From the balanced equation above,

1 mole of NaOH produced 1 mole of OH-.

Therefore, 3.16×10¯³ M NaOH will also produce 3.16×10¯³ M OH-.

Therefore, the concentration of NaOH is 3.16×10¯³ M

Next, we shall determine the number of mole of NaOH in the solution. This can be obtain as follow:

Molarity = 3.16×10¯³ M

Volume = 2 L

Mole of NaOH =?

Molarity = mole /Volume

3.16×10¯³ = mole of NaOH / 2

Cross multiply

Mole of NaOH = 3.16×10¯³ x 2

Mole of NaOH = 6.32×10¯³ mole

Finally, we shall convert 6.32×10¯³ mole of NaOH to grams

Mole of NaOH = 6.32×10¯³ mole

Molar mass of NaOH = 23 + 16 + 1 = 40g/mol

Mass of NaOH =?

Mole = mass /molar mass

6.32×10¯³ = mass of NaOH /40

Cross multiply

Mass of NaOH = 6.32×10¯³ x 40

Mass of NaOH =0.253 g

Therefore, 0.253g of NaOH is needed to prepare the solution.

first let us lay out the formula for potential

and kinetic energy:

pe = mgh

ke = (mv^2)/2

where: m=mass, v=velocity, g=gravitational

acceleration, h=height

calculating for mass using the known values of

pe:

340j = m (9.81 m/s^2) (50ft) (1m/3.28ft)

m = 2.27 kg

the law of conservation of energy states that

energy is neither created nor destroyed. therefore, the change in kinetic

energy from 50 ft to 35 ft would be equal to the change in potential energy

from 50 ft to 35 ft. however it would be opposite in signs since one is losing

while other is gaining.

ke(35ft) – ke(50ft) = - [ pe(35ft) – pe(50ft]

ke(50ft) = 0 since the brick is initially at rest

ke(35ft) = 340j - 2.27kg (9.81 m/s^2) (35ft)

(1m/3.28 ft)

ke(35ft)

= 102.38 j

radioactive decay occurs in unstable atomic nuclei – that is, ones that don't have enough binding energy to hold

the nucleus together due to an excess of either protons or neutrons.