Question 14 (1 point) Calculate the molarity of a solution made by dissolving 15.25 g lithium chloride (Lici)
in 250 mL of solution
61 M LICI
2
1.4 M LICI
5
0.36 M LICI
18
0.061 M Lici
0.0014 M LICI

Molarity = 1.4 M

Explanation:

Given data:

Mass of LiCl = 15.25 g

Volume of solution = 250 mL (250/1000 = 0.25 L)

Molarity of solution = ?

Solution:

Molarity is used to describe the concentration of solution. It tells how many moles are dissolve in per litter of solution.

Formula:

Molarity = number of moles of solute / L of solution

Now we will calculate the number of moles of LiCl.

Number of moles = mass/molar mass

Number of moles = 15.25 g/ 42.39 g/mol

Number of moles = 0.36 mol

Molarity:

Molarity = 0.36 mol / 0.25 L

Molarity = 1.4 M           (M= mol/L)

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 enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.