Answer:
<em>The pKa is 13.0.</em>
Explanation:
pKa + pKb = 14
Given, Kb of trimethylamine = 6.3 × 
pKb = - log (6.3 × )
= 1.0
⇒ pKa = 14 - pKb = 14 - 1.0
<u>pKa = 13.0</u>
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<em>Check: For most weak acids, pKa ranges from 2 to 13.</em>
Answer:
Dysprosium [Dy]=![[Xe]4f^{10}6s^2](https://tex.z-dn.net/?f=%5BXe%5D4f%5E%7B10%7D6s%5E2)
Americium [Am]=![[Rn]5f^77s^2](https://tex.z-dn.net/?f=%5BRn%5D5f%5E77s%5E2)
Dysprosium is a chemical element with symbol Dy and atomic number of 66. It is a rare earth metal and as it contains partially filled f sub shells, it belongs to f block. Xe is the nearest noble gas and has atomic number of 54.
Americium is a chemical element with symbol Am and atomic number of 95. It is a rare earth metal and as it contains half filled f sub shells, it belongs to f block. Radon is the nearest noble gas and has atomic number of 86.
Answer:
From the following enthalpy of reaction data and data in Appendix C, calculate ΔH∘f for CaC2(s): CaC2(s)+2H2O(l)→Ca(OH)2(s)+C2H2(g)ΔH∘=−127.2kJ
ΔHf°(C2H2) = 227.4 kJ/mol
ΔHf°(H2O) = -285.8 kJ/mol and
ΔHf°(Ca(OH)2) = -985.2 kJ/mol
(Ans)
ΔHf° of CaC2 = -59.0 kJ/mol
Explanation:
CaC2(s) + 2 H2O(l) → Ca(OH)2(s) + C2H2 (g) = −127.2kJ
ΔHrxn = −127.2kJ
ΔHrxn = ΔHf°(C2H2) + ΔHf°(Ca(OH)2) - ΔHf°(CaC2)- 2ΔHf°(H2O);
ΔHf°(CaC2) = ΔHf°(C2H2) + ΔHf°(Ca(OH)2) - 2ΔHf°(H2O) – ΔHrxn
Where
ΔHf°(C2H2) = 227.4 kJ/mol
ΔHf°(H2O) = -285.8 kJ/mol and
ΔHf°(Ca(OH)2) = -985.2 kJ/mol
ΔHf°(CaC2) =227.4 - 985.2 + 2x285.8 + 127.2 = -59.0 kJ/mol
ΔHf°(CaC2) = -59.0 kJ/mol
Since there are no choices given, my answer might not be what you're looking for. But it can definitely be a correct answer. The technique is called filtration. Filtration is a physical separation to separate the liquid and solid in a mixture. The mixture should be composed of an insoluble solid in a solvent. The mixture is usually passed through a semi-permeable barrier. In this case, a special piece of paper is used. The solvent is the liquid and the solid is the coffee bean grounds. Only the liquid can pass through the paper. The liquid that passes through the paper is generally called a filtrate.
Answer:
78.15 g
Explanation:
Number of moles of C₇H₆O₃ that reacted = mass/molar mass = 57.6g/126 gmol-1
Number of moles of C₇H₆O₃ = 0.457 moles of C₇H₆O₃
From the reaction equation;
1 mole of C₇H₆O₃ yields one mole of aspirin
0.457 moles of C₇H₆O₃ yields C₇H₆O₃ of aspirin
Hence theoretical yield of aspirin = 0.457 moles × 180 gmol-1 = 82.26g of aspirin
% yield = actual yield/theoretical yield ×100
Actual yield= % yield × theoretical yield/100
Actual yield = 95.0 × 82.26/100
Actual yield = 78.15 g
