How many grams of CaC12 (molar mass = 111 g/mol) are needed to prepare 100. mL of 0.100 M C1- (aq) ions?

5 H2O2(aq) + 2 MnO4-(aq) + 6 H+(aq) → 2 Mn2+(aq) + 8 H2O(l) + 5 O2(g) In a titration experiment, H2O2(aq) reacts with aqueous MnO4-(aq) as represented by the equation above. The dark purple KMnO4 solution is added from a buret to a colorless, acidified solution of H2O2(aq) in an Erlenmeyer flask. (Note: At the end point of the titration, the solution is a pale pink color.) Which element is being oxidized during the titration, and what is the element’s change in oxidation number?

When the equation below is balanced and the coefficients are reduced to the lowest whole-number terms, what is the coefficient of H2O(l)? . . . LiHCO3(aq) + . . . H2SO4(aq) → . . . Li2SO4(aq) + . . . H2O(l) + . . . CO2(g)

C6H12O6 + 6 O2 → 6 CO2 + 6 H2O   The reaction between C6H12O6 and O2 is represented by the balanced equation above. In an experiment, 0.30 mol of CO2 was produced from the reaction of 0.05 mol of C6H12O6 with excess O2. The reaction was repeated at the same temperature and in the same container, but this time 0.60 mol of CO2 was produced. Which of the following must be true?

5 H2O2(aq) + 2 MnO4-(aq) + 6 H+(aq) → 2 Mn2+(aq) + 8 H2O(l) + 5 O2(g) In a titration experiment, H2O2(aq) reacts with aqueous MnO4-(aq) as represented by the equation above. The dark purple KMnO4 solution is added from a buret to a colorless, acidified solution of H2O2(aq) in an Erlenmeyer flask. (Note: At the end point of the titration, the solution is a pale pink color.) Which of the following best describes what happens to the pH of the H2O2 solution as the titration proceeds? 

Compare the mass percent of Cu values that were determined by the two different experimental methods for finding the molarity of the brass solution. Which method do you think will provide a more accurate value? Justify your answer.

A student uses visible spectrophotometry to determine the concentration of CoCl2(aq) in a sample solution. First the student prepares a set of CoCl2(aq) solutions of known concentration. Then the student uses a spectrophotometer to determine the absorbance of each of the standard solutions at a wavelength of 510 nm and constructs a standard curve. Finally, the student determines the absorbance of the sample of unknown concentration. The figure presents a graph in the first quadrant of a coordinate plane. The horizontal axis is labeled “Molar Concentration of C o with a positive 2 charge, aqueous,” and the numbers 0 through 0.100, in increments of 0.020, are indicated. The vertical axis is labeled “Absorbance,” and the numbers 0.10 through 0.60, in increments of 0.10, are indicated. The line of best fit is drawn. The line begins where the axes meet. It moves steadily upward and to the right passing through the points 0.020 Molar and 0.11 absorbance, 0.040 Molar and 0.22 absorbance, 0.060 Molar and 0.33 absorbance, 0.080 Molar and 0.44 absorbance, and 0.100 Molar and 55 absorbance. There are 5 data points along the line. The data points at 0 Molar, 0.020 Molar, 0.065 Molar, and 0.100 Molar are on the line. The data point at 0.050 Molar is just below the line. The student made the standard curve above. Which of the following most likely caused the error in the point the student plotted at 0.050 M Co2+ (aq)?

Select the choice that best fits this statement: An oxidation-reduction reaction that is also a synthesis reaction

Which of the following compounds at 25°C and 1.0 atm contains an element in a +1 oxidation state?

2 F2(g) + 2 NaOH(aq) → OF2(g) + 2 NaF(aq) + H2O(l)   A 2 mol of F2(g) reacts with excess NaOH(aq) according to the equation above. If the reaction is repeated with excess NaOH(aq) but with 1 mol of F2(g), which of the following is correct?