CHM 130 Final Exam Questions With Correct Answers

The percent composition of water is - correct answers 11% H, 89% O In what units is molar mass typically expressed? - correct answers g/mol Which conversion factor would be used to convert from moles to moles of HCl? CH4 + 4Cl2 - CCl4 + 4HCl - correct answers 4 mol HCl / 4 mol Cl2 How many moles are present in 88.2 grams of NaCl? - correct answers 1.51 mol How many moles of are need to produce 6.23 moles of NH3? 3H2 + N2 = 2NH3 - correct answers 9.35 mol Using the percent compositions, what is the percentage of carbon in C6H12O6? - correct answers 39.99% C How many grams are present in 0.245 moles of H2? - correct answers 0.495 grams What is the percent composition of H3PO4? - correct answers 3.09%H, 31.60%P, 65.31%O How many moles are present in 1.21 x 10^23 atoms of Ga? - correct answers 0.201 mol How many grams are in 9.21 moles of H2CO3? - correct answers 571 g What is the molar mass of CO2? - correct answers 44.0 g/mol What is the energy being used for during periods "'B" and "D" on the heating curve below? - correct answers Weaken or overcome intermolecular attractions What phase transition is present at point B on the heating curve below? - correct answers Melting What shape does an ammonia (NH3) molecule have? - correct answers trigonal pyramidal What determines the polarity of a bond? - correct answers electronegativity difference only Compared to ionic and covalent bonds, the strength of intermolecular forces are - correct answers substantially less Compared to the particles of a gas, the particles of a liquid - correct answers do not completely fill their container At what temperature does this substance vaporize, according to the heating curve below? - correct answers 100 C Using VSEPR Theory, describe the shape of NI3 - correct answers trigonal pyramidal What type of bond occurs in a molecule of N2? - correct answers triple bond What determines the polarity of a molecule? - correct answers electronegativity difference and molecular shape Which of the following is not a property of gases? - correct answers gases molecules vibrate in a fixed position If the phases of matter are arranged in order of increasing disorder, the arrangement would be - correct answers solid, liquid, gas Rank the following intermolecular forces in order from weakest to strongest: - correct answers London Dispersion forces, Dipole-dipole forces, Hydrogen Bonding Forces In a tetrahedral molecule, how many unshared pairs of valence electrons does the central atom have? - correct answers none Using VSEPR Theory, describe the shape of SF2: - correct answers Bent In a polar bond, electrons are - correct answers shared unequally Which of the following molecules is polar? - correct answers HCl How many electron dots would be drawn around an atom of oxygen in its electron dot formula? - correct answers 6 What type of bond occurs between an atom of boron and iodine (given the electronegativity of B=2.0 and I=2.5)? - correct answers polar covalent bond In a Heating and Cooling Curve, what is occurring during the flat portions of the curve when the temperature is constant, and what is the energy being used to do? - correct answers it is changing the phase What is the primary type of intermolecular force present between adjacent CH2O molecules? - correct answers Dipole-dipole forces What is the name of the phase change that occurs when carbon dioxide goes from the solid state immediately to the gaseous state? - correct answers sublimation How many grams of HCl are required to prepare 250. mL of a 0.158 M solution of HCl? - correct answers 1.44 g What happens at the equivalence point in an acid/base titration? - correct answers there is an equal amount of moles of acid and base Neutral substances have a pH of exactly. - correct answers 7 A buffer's job is to - correct answers maintain the pH of the solution In the Bronsted-Lowry definition, an acid is a substance that - correct answers donates protons What is the pH of a solution with an [H+] of 1.0 x 10-3 M? - correct answers 3 What is the correct name of the acid HNO2 ? - correct answers nitrous acid Which of the following does not belong in this group? - correct answers LiOH The correct name of the acid HBr is? - correct answers hydrobromic acid Solutions with water as the solvent are called. - correct answers aqueous solutions The origin of the word acid relates to its taste, which is best described as. - correct answers sour Increasing the temperature of the solvent ____________________ the solubility of a solid solute and _______________________ the solubility of a gases solute. - correct answers increases, decreases If 18.9 J of heat was gained when 2.6 g of O2 was heated, what was the temperature change that occurred? (The specific heat of O2 is 0.954 J/g °C) - correct answers 7.6 C What is the oxidation number of chromium in K2Cr2O7? - correct answers +6 The units for specific heat are. - correct answers J/g °C How much heat is released when 27.6 g PCl3 cools from 83.1 °C to 55.6 °C? (The specific heat of PCl3 is 0.874 J/g °C). - correct answers 663 J A piece of aluminum metal at an initial temperature of 97.3°C was placed in a calorimeter containing 49.0g of water at an initial temperature of 22.0°C. The two were allowed to come to thermal equilibrium and the final temperature was 24.1°C. The specific heats of water and aluminum are 4.184 J/g °C and 0.902 J/g °C, respectively. What was the mass of the Al piece that was added? - correct answers 6.52 g The heat capacity of an object depends in part on its - correct answers mass If an iron ball is placed in a calorimeter at 40.0 °C and the water inside the calorimeter is 40.0 °C, the heat will - correct answers not flow at all since the two are already at thermal equilibrium. How much heat is lost when a solid iron nail weighing 23.00 g cools from 675.0 °C to 133.6 °C? (The specific heat of Fe is 0.450 J/g °C). - correct answers 5603 J A 28.4 g sample of an unknown metal is heated to 39.4 °C, then is placed in a calorimeter containing 50.0 g of water. Temperature of water increases from 21.00 °C to 23.00 °C. What is the specific heat of this metal in this problem? - correct answers 0.898 J/g °C. What is the oxidation number of phosphorus in PO4^-3? - correct answers +5 Which is a device used to measure the heat absorbed or released during a chemical or physical process? - correct answers calorimeter Which substance is being oxidized in the following reaction? 4Na + O2 - 2Na2O - correct answers Na What mass of benzene is cooled from 83.8 °C to 77.1 °C when 167 J of energy is transferred out of the system? (The specific heat of benzene is 1.740 J/g °C). - correct answers 14.3 g Heat is measured in. - correct answers Joules