Which one of the following is the highest temperature? A) 302 K B) 38°C C) 96°F D) none of the above E) the freezing point of water 7. Which of the following liquids has the greatest density? A) 3.5 cm3 with a mass of 10 g B) 13 cm3 with a mass of 23 g C) 0.022 cm3 with a mass of 0.10 g D) 54 cm3 with a mass of 45 g E) 210 cm3 with a mass of 12 g 8. Gold has a density of 0.01932 kg/cm3.
Pb (NO3) 2 10. A compound is 42.3 % C, 5.94 % H, 32.9 % N, and 18.8 % O and has a molecular mass of 425.25 g/mol. Calculate the empirical and molecular formula. C15H25N10O5 11. How many moles of Al2O3 are produced by the reaction 200. g Al?
1. 25 cm3 of a solution of 0.1 moldm-3 NaOH reacts with 50 cm3 of a solution of hydrochloric acid. What is the molarity of the acid? 2. 25.0 cm3 of a 0.10 moldm-3 solution of sodium hydroxide was titrated against a solution of hydrochloric acid of unknown concentration.
Which of these physical changes would require the liberation of energy? a. condensation of steam to form liquid water b. melting of ice c. boiling of water d. all of the above e. none of the above ____ 5. Which answer lists all the substances below that are compounds and not any elements or mixtures? I. II. III.
Which would have the longer wavelength, light with a frequency of 4.5 X 1014 Hz or light with a frequency of 6.19 X 1014 Hz? (4.5 X 1014 Hz) ______________12. Find the frequency of light if its wavelength is 7.3 X 105 5 picometers. (4.1 X 1014 Hz) ______________13. Find the wavelength in centimeters of light whose frequency is 7.00 X 1016 Hz.
An aqueous solution of potassium chloride is mixed with an aqueous solution of sodium nitrate. Identify the solid in the balanced equation. A) KCl B) NaNO3 C) KNO3 D) NaCl E) There is no solid formed when the two solutions are
The precipitate(s) for the above reaction is/are: A) Silver nitrate B) Aluminum bromide C) Silver bromide D) Aluminum nitrate E) There is no precipitate 18 – 37: For each of the two REDOX reactions below, perform the following: A) Balance the following equation and place the final answer in the boxes provided; show all work on the exam pages. B) Identify the oxidizing and reducing reagents. C) Assign the oxidation numbers to the elements in bold on both sides of the equation. D) Identify the oxidation and reduction half-reactions by placing LEO and GER, respectively, above the arrows in each half-reaction. E) NOTE that illegible writing will not be graded.
or Reaction w/cold H2O:None Solub. or Reaction w/hot H2O: None Litmus test: Blue turned white. Red had no reaction. Dilute HCl: Bubbles up and fumes form, the zinc became darker in color. Dilute NaOH: None Substance: MgO Color: White Odor: Yes Effect of Heat: None Solub.
of moles of Cu2O = no. of moles of O = 0.00875 mol (critical step) mass of Cu2O = 0.00875 x (63.5 x 2 + 16.0) = 1.25125 g percentage by mass of Cu2O = (1.25125 )/2.02 x 100 % = 61.9 % Common mistake: no. of moles of (Al2O3 + Cu2O) = Comment: no. of moles = Example 2 0.144 g of a binary compound of aluminium and carbon reacts with an excess of water to produce a gas. This gas burns completely in oxygen to form water and 72 cm3 of carbon dioxide only.
A. II only B. III only C. II and III D. I only 6. A hydrate is a A. buffer solution of water B. compound in which hydrogen is combined with an element less electronegative than itself C. compound containing a definite number of water molecules in its chemical composition D. salt containing the hydroxyl radical 7. Two moles of hydrogen react with 1 mole of oxygen to produce which of the following? A. 1 mole of water B.