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3 years ago

2.5 \ 4620 to the significant number

1 answer:

4 0

0.0005411
0.00054 is the real answer
you use the one with the least significant figures as the reference of how many to use.

101 three sig figs
001 one sig figs as well as 0.001
9.000 four sig figs

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When 18.0 mL of a 8.43×10-4 M cobalt(II) fluoride solution is combined with 22.0 mL of a 9.72×10-4 M sodium hydroxide solution d

Eva8 [605]

Answer:

Q = 1.08x10⁻¹⁰

Yes, precipitate is formed.

Explanation:

The reaction of CoF₂ with NaOH is:

CoF₂(aq) + 2 NaOH(aq) ⇄ Co(OH)₂(s) + 2 NaF(aq).

The solubility product of the precipitate produced, Co(OH)₂, is:

Co(OH)₂(s) ⇄ Co²⁺(aq) + 2OH⁻(aq)

And Ksp is:

Ksp = 3x10⁻¹⁶= [Co²⁺][OH⁻]²

Molar concentration of both ions is:

[Co²⁺] = 0.018Lₓ (8.43x10⁻⁴mol / L) / (0.018 + 0.022)L = 3.79x10⁻⁴M

[OH⁻] = 0.022Lₓ (9.72x10⁻⁴mol / L) / (0.018 + 0.022)L = 5.35x10⁻⁴M

Reaction quotient under these concentrations is:

Q = [3.79x10⁻⁴M] [5.35x10⁻⁴M]²

Q = 1.08x10⁻¹⁰

As Q > Ksp, the equilibrium will shift to the left producing Co(OH)₂(s) the precipitate

8 0

4 years ago

Lavoisier's discovery that air was not a substance but rather a mixture of nitrogen and oxygen is described as history-making. w

Taya2010 [7]

Antoine Lavoisier was part of a wealthy family in Paris. He pursued to study science upon realizing that chemistry or the study of the elements was not a well-studied field. His discovery of that air was a mixture of nitrogen and oxygen gave rise to the concept of COMBUSTION after repeating the experiments made by Priestly using mercury and other metal oxides.

The event was such a history-making because it disproved that concept that air was a pure substance along with 3 others: earth, fire, and water.

6 0

3 years ago

Which group of elements on the periodic table can have more than one possible charge? noble gases alkali metals alkaline earth m

Kamila [148]

Transition Metals can have more than one possible charge.

4 0

4 years ago

The Ksp of yttrium iodate, Y(IO3)3 , is 1.12×10−10 . Calculate the molar solubility, s , of this compound.

torisob [31]

Answer:

1.427x10^-3mol per L

Explanation:

$Y(IO_{3} )_{3} ---- Y^{3+} +IO_{3} ^{3-}$

I could use ⇌ in the math editor so I used ----

from the question each mole of Y(IO3)3 is dissolved and this is giving us a mole of Y3+ and a mole of IO3^3-

Ksp = [Y^3+][IO3-]^3

So that,

1.12x10^-10 = [S][3S]^3

such that

1.12x10^-10 = 27S^4

the value of s is 0.001427mol per L

= 1.427x10^-3mol per L

so in conclusion

the molar solubility is therefore 1.427x10^-3mol per L

3 0

3 years ago

Ammonium nitrate is an ingredient in cold packs used by sports trainers for injured athletes. Calculate the change in temperatur

Ronch [10]

Answer:

See explanation

Explanation:

First, we need to use the correct expression:

Q = m*Cp*ΔT (1)

Q = n*ΔH (2)

These are the 2 expressions to calculate heat or energy.

Now, we want to know the change of temperature of the nitrate in water after being added, so with the innitial data of nitrate, we can calculate heat using the second expression. First, we need to calculate moles with the molecular mass:

n = m/MM

n = 42/80.1 = 0.52 moles

With these moles, we can calculate heat with the ΔH of this reaction:

Q = 0.52 * 25.7 = 13.364 kJ or 13,364 J

However, this heat as is being absorbed, the value would be negative.

Now that we have heat, we can use expression (1) and plug these values to solve for ΔT, but before, we need to know the total mass of the solution (water + nitrate)

m = 250 + 42 = 292 g

now, solving for ΔT:

-13,364 = 292 * 4.18 * ΔT

ΔT = -13,363 / (292 * 4.18)

ΔT = -10.95 °C

3 0

3 years ago