Questions asked by jasmineswen

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• Equal volumes of #"0.25 M"# #"HNO"_2# and #"0.25 M"# #"HNO"_3# are titrated separately with #"0.25 M"# #"KOH"#. Which would be the same for both titrations?
  
• A reaction is endothermic with H=100 kJ/mol. If the activation enthalpy of the forward reaction is 140 kJ/mol, what is the activation enthalpy of the reverse reaction? I know the answer is 40 kJ/mol but I’m not quite sure how to get there, thanks!
  
• What is the pH of a solution made by mixing 200 mL of 0.0657 M NaOH, 140 mL of 0.107 M HCl, and 160 mL of H2O? I know that the answer is 2.43, but could someone please explain how? Thank you so much!!!!
  
• What is the pH of a solution that is 0.20 M in HF and 0.40 M in NaF? [Ka = 7.2*10^-4] I know the answer is 3.44 but could someone please explain how they got it? Thank you so much!!!! (:
  
• How many unpaired electrons are in a gaseous Co 3+ ion in its ground state? The answer is 4, but I don’t understand how. Could someone please explain? Thank you!
  
• 30.0 mL of 0.10 M Ca(NO3)2 and 15.0 mL of 0.20 M Na3PO4 solutions are mixed. After the reaction is complete, which of these ions has the lowest concentration in the final solution?
  
• A 75 mL solution that is 0.10 M in HC2H3O2 and 0.10 M in NaC2H3O2 has a pH of 4.74. Which of the following actions will change the pH of this solution?
  
• Which species contains only covalent bonds?
  
• Which of the following is a weak electrolyte in aqueous solution? A) HF B) NaF C) HCl D) KCl Could someone please explain why the answer is HF, thank you so much!
  
• When 1.0 mol of H2O2 decomposes to form H2O and O2, 103 kJ of energy is released. Given the bond energies below, what is the bond energy of the O-O single bond in H2O2?
  
• What is the #K_(sp)# for silver chloride?