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Artist 52 [7]
3 years ago
15

A pure substance that is present before a reaction but not after Super Confused

Chemistry
1 answer:
never [62]3 years ago
4 0

Explanation:

Pure subsance is a substance that is made up of only one type of particle - each piece is the same throughout.

Being present before the reaction but not after means it's no the same (it couldve evaporated)

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What does the atomic number ask​
Alik [6]

I'm not sure what it asks, but it answers

  1. how many protons are in the nucleus
  2. how many electrons are in the atom
  3. where it sits in the periodic table
  4. If the periodic table is divided in the modern way, it gives a good indicator of whether you are speaking about a metal, a non metal or neither.
5 0
3 years ago
Read 2 more answers
Calculate the values of ΔU, ΔH, and ΔS for the following process:
ladessa [460]

Answer:

ΔU = 45.814 KJ

ΔH = 46.4375 KJ

ΔS = 18.76 J/K

Explanation:

            H2O(l)        →          H2O(l)                →              H2O(steam)

   298.15K, 1atm   ΔHp     373.15K,1atm       ΔHv         373.15K,1 atm

∴ ΔHp = Qp = nCpΔT

∴ n H2O = 1 mol

∴ Cp,n = 75.3 J/mol.K

∴ ΔT = 373.25 - 298.15 = 75 K

⇒ Qp = (1 mol)*(75.3 J/mol.K)*(75K) = 5647.5 J

⇒ ΔHp = 5647.5 J = 5.6475 KJ

⇒ ΔH = ΔHp + ΔHv

∴ ΔHv = 40.79 KJ/mol * 1 mol = 40.79 KJ  

⇒ ΔH = 5.6475 KJ + 40.79 KJ = 46.4375 KJ

ideal gas:

∴ ΔH = ΔU + PΔV

∴ V1 = nRT1/P1 = ((1)*(0.082)*(298.15))/1 = 24.45 L

∴ V2 = nRT2/P2 = ((1)*(0.082)*(373.15))/ 1 = 30.59 L

⇒ ΔV = V2 - V1 = 6.15 L * (m³/1000L) = 6.15 E-3 m³

∴ P = 1 atm * (Pa/ 9.86923 E-6 atm) = 101325.027 Pa

⇒ ΔU = ΔH - PΔV = 46.4375 KJ - ((101325.027 Pa*6.15 E-3m³)*(KJ/1000J))

⇒ ΔU = 46.4375 KJ - 0.623 KJ

⇒ ΔU = 45.814 KJ

∴ ΔS = Cv,n Ln (T2/T1) + nR Ln (V2/V1)

⇒ ΔS = (75.3) Ln(373.15/298.15) + (1)*(8.314) Ln (30.59/24.45)

⇒ ΔS = 16.896 J/K + 1.863 J/K

⇒ ΔS = 18.76 J/K

3 0
3 years ago
What volume of a 1.50 m hcl solution should you use to prepare 2.00 l of a 0.100 m hcl solution?
katen-ka-za [31]
<span>(2.00 L) x (0.100 M HCl) / (1.50 M HCl) = 0.133 L</span>
8 0
3 years ago
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Of the metals pb hg na and mg which will not spontaneously donate electrons to copper in solution
marta [7]

Answer : Hg (Mercury)


Explanation : In the given series of elements Na falls after the Cu in the reactivity series, for Pb it also falls after Cu, and for Mg it is the same.


Only Hg which is mercury can spontaneously donate its electrons to copper in the solution because it falls before Cu in the reactivity/activity series.

3 0
3 years ago
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A 0.100 m solution of a monoprotic weak acid has a ph of 3.00. what is the pka of this acid?
Lelechka [254]
Answer is: pKa for the monoprotic acid is 5.<span>
Chemical reaction: HA(aq) </span>⇄ A⁻(aq) + H⁺<span>(aq).
c(monoprotic acid) = 0.100 M.
pH = 3.00.
[A</span>⁻] = [H⁺] = 10∧(-3).<span>
[A</span>⁻] = [H⁺] = 0.001 M; equilibrium concentration.<span>
[HA] = 0.1 M - 0.001 M.
[HA] = 0.099 M.
Ka = [A</span>⁻]·[H⁺] / [HA].<span> 
Ka = (0.001 M)² / 0.099 M.
Ka = 0.00001 M = 1.0·10</span>⁻⁵ M.
<span>pKa = -logKa = 4.99.

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7 0
3 years ago
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