A chemist dissolves 249.mg of pure perchloric acid in enough water to make up 380.mL of solution. Calculate the pH of the solution. Be sure your answer has the correct number of significant digits.

pH = 2.18

Explanation:

Perchloric acid (HClO₄) is a strong acid. This means that in an aqueous solution it completely dissociates into H⁺ and ClO₄⁻ species.

First we convert 249 mg HClO₄ into moles, using its molecular weight:

Because it is a strong acid, 2.49 mmol HClO₄ = 2.49 mmol H⁺

We calculate the molar concentration of H⁺:

Finally we calculate the pH of 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

c. 75.7

i think that is the right