C125

CHEM-C125 ASSESSMENT TEST QUESTIONS WITH CORRECT ANSWERS A solid sample contains both NaOH and NaCl. 0.500 g of this solid sample was dissolved in water to make a 20.0 mL solution and then this solution was titrated by 0.500 mol/L HCl solution. If 22.5 mL of HCl was used to reach the end point, what is the mass % of NaOH in the original solid sample? NaOH + HCl --> NaCl + H2O - Answer- 90 During titration, it is very common to have some NaOH spilled to the inside wall of Erlenmeyer fl...

C125 MIDTERM QUIZ QUESTIONS AND ANSWERS Predict products of the following reaction: Cl2 + KI --> - Answer- KCl + I2 What is the reducing agent in the following reaction? Cu(s) + 2 AgNO3(aq) --> Cu(NO3)2(aq) + Ag(s) - Answer- Cu When a colorless Ba(NO3)2 solution mixes with a colorless Na2SO4 solution: - Answer- a precipitate will form A test tube has a colorless aqueous layer of NaI solution and an colorless organic layer of methylene chloride. When a few mL of colorless ...

C125 EXAM-QUESTIONS WITH CORRECT ANSWERS 3.Write a balanced chemical equation noting all species and states of matter 4.Break up any aqueous compound into its ions to write the total ionic equation (including states of matter) 5.Cancel out any spectator ions 6.Write the remaining species as the net ionic equation Endothermic - Answer- - Absorbs heat from the surroundings - Becomes colder; requiring a gain of energy Exothermic - Answer- - Releases energy to it surroundings ...

C125 STUDY GUIDE EXAM QUESTIONS AND ANSWERS electron delocalization - Answer- Resonance structures lower the energy through.... sp3 - Answer- What is the hybridization of the central atom in H2O? yes - Answer- can both bonding and antibonding molecular orbitals have nodal planes? perpendicular to internuclear axis - Answer- sigma and pi antibonding molecular orbitals always have a nodal plane where? 2p - Answer- If we apply the HOMO and LUMO concepts in atomic orbitals, we will h...

CHEM-C125 EXAM #3 QUESTIONS WITH CORRECT ANSWERS ten-fold difference in concentration of conjugate pairs - Answer- any pH change of 1 unit is a ... the choice of the system and thus the Ka. the ratio of the concentration of conjugate pairs. - Answer- what does the pH of a buffer depend upon? added strong acid or added strong base - Answer- buffering capacity: has the ability to absorb... need to prepare a buffer solution with a specific pH; assume [base] = [acid] - Answer- how to ch...

C125 EXAM REVIEW QUESTIONS WITH CORRECT ANSWERS Red and purple are two lines of hydrogen lamp. Which one is correct when comparing these two lines? - Answer- -Red line has smaller energy than the purple one -Red line has longer wavelength than the purple one According to Bohr's Model, which one is correct about a transition from n=2 to n=1 in a hydrogen atom? - Answer- It is a transition from an excited state to a ground state The lines observed in H-lamp are parts of Balmer Series. ...

C125 MIDTERM REVISION EXAM QUESTIONS WITH CORRECT ANSWERS A student experimentally determined the mass % compisition of Ca in CaCO3 to be 38.9%. What is the real mass % composition of CaCO3? What is the % error? - Answer- real = 40.04% error = 2.858% Recall the procedure (chemical measurements). How would the following source of errors affect calculated density of water? A balance was improperly calibrated and always weigh masses 1.0g less than the real masses - Answer- no effect (take...

C125 REVISION EXAM QUESTIONS WITH COMPETE SOLUTIONS In the molar mass lab, why was it important to level the water in the graduated cylinder with that in the through? - Answer- so that the pressure inside the cylinder would equal atmospheric pressure butane hazards - Answer- butane lighter fluid is extremely flammable. it is a mixture of two isomers both of which boil at temperatures below 0°C at 1 atm pressure. the gas is stored as a liquid in the pressurized container. However, when th...

C125 MIDTERM EXAM QUESTIONS AND ASWERS If 11.3 g of NaCl is dissolved in 100. g of water, what is the percent by mass (mass%) concentration of NaCl in the solution? Note: 1. Use three sig figs for your final answer. 2. Do not enter your answer as fractions. For example, if you think 30% is the correct answer, enter either "30" or "30%". Do NOT enter "0.30". - Answer- 10.2 How many moles of NaOH will be needed to neutralize 0.86 mol of H2SO4? The following equation is NON-bal...

If we apply the HOMO and LUMO concepts in atomic orbitals, we will have HOAO (Highest Occupied Atomic Orbitals) and LUAO (Lowest Unoccupied Atomic Orbitals). What is the LUAO of Na atom? - Answer- 3p Which one is correct about the bond lengths in PCl5? Equatorial bonds are longer because they experience smaller repulsion The axial bonds are shorter because they are far away from other bonds All P-Cl bonds have the same bond length. Axial bonds are longer because they experienc...