To lift fingerprints from a crime scene, a solution of silver nitrate is sprayed on a surface to react with the sodium chloride left behind by perspiration. What is the molarity of a silver nitrate solution if 42.8 mL of it reacts with excess sodium chloride to produce 0.148g of precipitate according to the following reaction? AgNO3(aq)+NaCl(aq) --> AgCl(s)+NaNO3(aq)
A) 2.41 x 10^-2 M
B) 0.0229 M
C) 6.66 x 10^-2 M
D) 3.2 x 10^-3 M
E) 2.29 x 10^2 M

A) 2.41 * 10^-2 M

Explanation:

Here we go from grams of percipitate to moles of Silver nitrate because we already know NaCl is excess so we don't care about that.

Now that we have moles we know molarity is moles/litres so we just plug it in:

Molarity = mol/litres = 0.00103/0.0428 L = 0.0241 M or 2.41 * 10^-2 M

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

the answer is definitely c.