C125 final Study guides, Class notes & Summaries

PCl5 - Answer- All of the following molecules have all bonds being equivalent except: SF6 CH4 NH3 PCl5 lone pair to lone pair - Answer- Which of the following has the largest repulsion, assuming that all the angles between electron pairs are identical? -They are all the same because they all contain the same number of electrons -lone pair to lone pair - bonding to bonding pair -lone pair to bonding pair square planar - Answer- What is the molecular geometry of XeF4? none of ...

The lines observed in H-lamp are parts of Balmer Series. All these lines are due to a transition from various higher n value to a common n. What is this common lower n value for all these lines? - Answer- 2 The bright violet line of Hg lamp has a wavelength of 435.8 nm. What is the energy of the photon associated with this emission line? - Answer- 4.56*10^-19 J Given: In Atomic Spectra lab, a student obtained his best-fit line equation to be y = 0.29 x + 46.8 when he plotted his Vernier re...

Rearrange the following equation to solve for P. (P+a)(V-b)=nRT - Answer- P= nRT/V-b -a What is the y-intercept if B is plotted on y-axis and A is plotted on x-axis? - Answer- -20 Interpolation - Answer- estimating a value within the range of measured data extrapolation - Answer- projection; conjecture; V. extrapolate: infer (unknown information) from known information Assume that multiple trials of an experiment were performed. What is the quantity that describes how closely the re...

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 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 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...

Rearrange the following equation to solve for V. (P+a)(V-b)=nRT - Answer- V= (nRT/P+a) +b In an experiemnt, the best-fit-line equation between Absorbance (A, unitless) and concentration (c, mg/mL) is used to calculate the concentration of Fe. Based on the best-fit line equation given below, what is the concentration of Fe if the absorbance is 1.25? A = 851 c + 0.03 - Answer- 0.0014 In y=kx + b, b is - Answer- y-intercept All of the following numbers have three sig figs EXCEPT: 1...

If you accidentally spilled some dilute HNO3 on the ground, what should you do? - Answer- Use excessive NaHCO3 to neutralize it and then clean it. Random errors may affect the... - Answer- precision but not the accuracy. Phenolphthalein is the pH indicator used in Vinegar Analysis lab. Which one of the following solutions may turn pink if a few drops of phenolphthalein is added? - Answer- 10 mL of a 0.20M HCL solution combined with 15 mL of 0.20M NaOH solution A balance always reads 0.1...

Aliquot - Answer- - *Portion of measurement added* - Example: "In this experiment, we will be using an *aliquot* of 10 mL of water for each trial Sig Fig Rules (Significant) - Answer- - Any non-zero digit is a sig fig - Zeros between non-zeros are sig figs - Zeros to the right of the last non-zero digit are sig figs Sig Fig Rules (Insignificant) - Answer- - Zeros to the left of the first non-zero are NOT sig figs Calculations Rules for Sig Figs (+/-) - Answer- - Focus on decim...