Zadania z chemii IB SL

(b) Outline two safety precautions that must be taken during the preparation of propanoic acid, besides wearing a lab coat and safety goggles.

(c) After 30 minutes, the student stopped heating the mixture and titrated a sample of the solution remaining in the flask with NaOH to determine the experimental yield of propanoic acid. Explain why the titrated sample will give an incorrect value for the…

(d) The student used distillation to obtain pure propanoic acid from the reaction mixture. State two impurities, apart from unreacted propan-1-ol, that were present in the propanoic acid before distillation.

(i) State the number of protons, electrons and neutrons in $\ce{^{85}Rb+}$. (ii) State the full electron configuration for $\ce{^{85}Rb+}$. (iii) The relative atomic mass, $A_r$, of Rb is 85.47. Isotope Mass Percent abundance $\ce{^{x}Rb}$ 72.17 %…

(i) Explain why Rb has a lower first ionization energy than strontium, Sr. (ii) Outline why Rb has a lower electronegativity than potassium, K.

(i) Write the equation for the reaction of Rb with water, $\ce{H2O}$, including state symbols. (ii) Describe the type of bonding in $\ce{Rb}$ and in $\ce{H2O}$, and explain how the valence electrons in each produce that type of bond.

What is the correct electron configuration of the selenium atom? A. $1s^2 2s^2 2p^6 3s^2 3p^6 3d^{10} 4s^2 4p^4$ B. $1s^2 2s^2 2p^6 2d^{10} 3s^2 3p^6 4s^2 4p^4$ C. $1s^2 2s^2 2p^6 3s^2 3p^6 3d^{10} 4s^2 4p^6$ D. $1s^2 2s^2 2p^6 3s^2 3p^6 3d^{8} 4s^2 4p^6$

(i) Determine the enthalpy of combustion of pentane, in kJ mol$^{-1}$, using table 12 in the data booklet. $\ce{C5H12(g) + 8O2(g) -> 5CO2(g) + 6H2O(g)}$ (ii) Calculate the mass, in g, of carbon dioxide, $\ce{CO2}$, produced when 45.0 g of pentane react with…