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3 years ago

If I add 475mL of water to 75.0mL of a 0.315M NaOH solution, what will the molarity of the diluted solution be?

1 answer:

5 0

Answer is: the molarity of the diluted solution 0,043 M.
V(NaOH) = 75 mL ÷ 1000 mL/L = 0,075 L.
c(NaOH) = 0,315 M = 0,315 mol/L.
n(NaOH) = c(NaOH) · V(NaOH).
n(NaOH) = 0,075 L · 0,315 mol/L.
n(NaOH) = 0,023625 mol.
V(solution) = 0,475 L + 0,75 L.
c(solution) = 0,023625 mol ÷ 0,550 L.
c(solution) = 0,043 mol/L.

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A 251 ml sample of 0.45M HCl is added to 455 mL of distilled water. What is the molarity of the

Oksi-84 [34.3K]

We are given:

251 mL sample of 0.45M HCl added to 455 mL distilled water

Whack a mole! (finding the number of moles):

We know that in order to find molarity, we use the formula:

Molarity = number of moles / Volume (in L)

so, number of moles is:

Number of moles = Molarity * Volume(in L)

now let's plug the values for the HCl solution to find the number of moles

Number of moles = 0.45M * 0.251 L

Number of moles = 0.113 moles

Time to concentrate (finding the final concentration):

Total final volume = 251 mL + 455 mL = 706 mL = 0.706 L

Number of moles of HCl = 0.113 moles

Molarity = Number of moles / Volume (in L)

Molarity = 0.113 / 0.706

Molarity = 0.16 M

___________________________________________________________

BONUS METHOD TIME!!!

We know the relation:

M1 * V1 = M2 * V2

where M1 and M2 are the initial and final molarities and V1 and V2 are initial and final volumes respectively

notice that I didn't mention that the volume has to be in Liters, that's because of the units being concerned with both sides of the equation, say I have the volume in mL and want to convert both these volumes to L, I would divide both sides by 1000, which would NOT change the overall value

Now, plugging values in this equation

(0.45) * (251) = (251 + 455)* (M2)

112.95 = (706)(M2)

M2 = 112.97/706 [dividing both sides by 706]

M2 = 0.16 Molar

8 0

2 years ago

The incredible catalytic power of enzymes can perhaps best be appreciated by imagining how challenging life would be without jus

ioda

Answer:

t = 7.58 * 10¹⁹ seconds

Explanation:

First order rate constant is given as,

k = (2.303 /t) log [A₀] /[Aₙ]

where [A₀] is the initial concentraion of the reactant; [Aₙ] is the concentration of the reactant at time, t

[A₀] = 615 calories;

[Aₙ] = 615 - 480 = 135 calories

k = 2.00 * 10⁻²⁰ sec⁻¹

substituting the values in the equation of the rate constant;

2.00 * 10⁻²⁰ sec⁻¹ = (2.303/t) log (615/135)

(2.00 * 10⁻²⁰ sec⁻¹) / log (615/135) = (2.303/t)

t = 2.303 / 3.037 * 10⁻²⁰

t = 7.58 * 10¹⁹ seconds

8 0

2 years ago

Why would the presence of oxygen bubbles be a good indicator of photosynthesis occurring?

irina1246 [14]

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6 0

2 years ago

How many molecules are present in 4.5 moles of H2O?

Gekata [30.6K]

Answer:

Mole of the H2O = 4.5

Number of molecules =4.5 multipled by avogadro's number.

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2 years ago

As you were climbing a a mountain, you noticed that rocks were crumbling below your feet and moving down the mountain. What two

Flauer [41]

Answer:

Weathering and erosion

Explanation:

Weathering can be explained as the breaking down of rocks/minerals on the surface of the Earth as a result of contact with biological organism, water, air and other factors

. There are 3 common types of weathering which are;

1) physical weathering

2) biological weathering

3) chemical weathering

Erosion can be regarded as a geological process, whereby earthen material are been transported away by natural forces, these forces could be wind as well as water.

Therefore, as you were climbing a a mountain, you noticed that rocks were crumbling below your feet and moving down the mountain. What is observed are weathering and erosion processes.

After the weakening and broken up of the rock by weathering then erosion transport the bit of the rock down the mountain as you are climbing, which means the "weathering process" breakdown and the "erosion process" involves the transport or movement of the bit of the rocks

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3 years ago