Suppose that you have a 60.0% solution of NaOH. How many milliliters of water must be added to 30.0 mL of this solution to prepare a 35.0% solution of NaOH

21.4 mL

Explanation:

Firstly, one has to understand some "terms" here before proceeding.

60.0% solution of NaOH means 60g of NaOH salt/solute in 100 mL of water

35.0% solution of NaOH also means 35g of NaOH salt/solute in 100 mL of water.

To solve the problem in the question, we say, if 60 g dissolves in 100 mL, how many grams will be present in 30 mL

60 ⇒ 100

? ⇒ 30

? = 60 × 30/100

? = 18g

18 g of NaOH will be present in 30 mL of the solution making the % weight per volume to be 18/30

Thus, if we want to achieve 35% solution of NaOH from 18/30, the total amount of water that will be required will be ?

35 ⇒ 100

18 ⇒ ?

? = 18 × 100/35

? = 51.4 mL

Hence, the milliliters of water that must be added is 51.4 - 30 = 21.4 mL

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