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3 years ago

Describe exothermic reaction please

Chemistry

1 answer:

nordsb [41]3 years ago

7 0

Answer: Exothermic reactions are reactions or processes that release energy, usually in the form of heat or light.

Explanation: In an exothermic reaction, energy is released because the total energy of the products is less than the total energy of the reactants.

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The value of Ksp for PbCl2 is 1.6 ×10-5. What is the lowest concentration of Cl-(aq) that would be needed to begin precipitation

Dovator [93]

Answer:

0.04 M is the lowest concentration of chloride ions that would be needed to begin precipitation.

Explanation:

Concentration of lead nitarte = $[Pb(NO_3)_2]=0.010 M$

$Pb(NO_3)_2(aq)\rightleftharpoons Pb^{2+}(aq)+2NO_{3}^{-}(aq0$

1 Mole of lead nirate gives 1 mole of lead ion.

Concentration of lead ion in the solution = $1\times 0.010 M= 0.010 M$

$Pb(Cl)_2(aq)\rightleftharpoons Pb^{2+}(aq)+2Cl^{-}(aq0$

Concentration of chloride ions = $[Cl^-]$

The value of $K_{sp} for [tex]PbCl_2= 1.6\times 10^{-5}$

$K_{sp}=[Pb^{2+}][Cl^{-}]^2$

$1.6\times 10^{-5}=0.010 M\times [Cl^{-}]^2$

$[Cl^-]=0.04 M$

0.04 M is the lowest concentration of chloride ions that would be needed to begin precipitation.

3 0

4 years ago

The Ksp for calcium fluoride, CaF2, is 1.5 x 10-10. a) Excess solid calcium fluoride is added to 1.00 L of pure water. Calculate

solniwko [45]

Answer:

a) [ Ca2+ ] = 3.347 E-4 mol/L

b) [ Ca2+ ] = 1.5 E-8 mol/L

Explanation:

CaF2 ↔ Ca2+ + 2F-

S S 2S......in the equilibrium

⇒ Ksp = 1.5 E-10 = [ Ca2+ ] * [ F- ]² = S * ( 2S )² = 4S³

⇒ S = ∛ ( 1.5 E-10 / 4 )

⇒ S = ∛ 3.75 E-11

⇒ S = 3.347 E-4 mol/L

⇒ [ Ca2+ ] = S = 3.347 E-4 mol/L

b) NaF ↔ Na+ + F-

0.10 M 0.10 0.10

CaF2 ↔,Ca2+ + 2F-

S S 2S + 0.10

⇒ Ksp = 1.5 E-10 = [ Ca2+ ] * [ F- ]² = S * ( 2S + 0.10 )²

∴∴ the Concentration: 0.10 M >>>> Ksp ( 1.5 E-10 ), son we can despise S as adding.

⇒ 1.5 E-10 = S * ( 0.10 )² = 0.01 S

⇒ S = 1.5 E-10 / 0-01

⇒ S = 1.5 E-8 mol/L

⇒ [ Ca2+ ] = S = 1.5 E-8 mol/L

5 0

3 years ago

17 Which substance can not be broken down by a chemical change?(1) ammonia (3) propanal

lyudmila [28]

Zirconium cannot be broken down by a chemical change, because it is an element. The others are all molecules.

6 0

4 years ago

Read 2 more answers

Find the age t of a sample, if the total mass of carbon in the sample is mc, the activity of the sample is a, the current ratio

kkurt [141]

should be 7.57*10^3 years

4 0

4 years ago

A 1.25 g sample of aluminum is reacted with 3.28 g of copper (II) sulfate. What is the limiting reactant? 2Al(s) + 3CuSO4(aq) →

vova2212 [387]

Answer:

Copper (II) sulfate

Explanation:

Given reaction is

2Al(s) + 3CuSO4(aq) → Al2(SO4)3(aq) + 3Cu(s)

Amount of aluminum = 1·25 g

Amount of copper (II) sulfate = 3·28 g

Atomic weight of Al = 26 g

Molecular weight of CuSO4 ≈ 159·5

Number of moles of Al = 1·25 ÷ 26 = 0·048

Number of moles of CuSO4 = 3·28 ÷ 159·5 = 0·021

From the above balanced chemical equation for every 2 moles of aluminum, 3 moles of copper (ll) sulfate will be required

So for 1 mole of Al, 1·5 moles of copper (ll) sulfate will be required

For 0·048 moles of Al, 1.5 × 0·048 moles of copper (ll) sulfate will be required

∴ Number of moles of copper (ll) sulfate required = 0·072

But we have only 0·021 moles of copper (ll) sulfate

As copper (ll) sulfate is not there in required amount, the limiting reactant will be copper (ll) sulfate

∴ The limiting reactant is copper (ll) sulfate

7 0

3 years ago