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Chemistry Final
Final Chemistry Exam
| Question | Answer |
|---|---|
| Hydrogen peroxide will decompose if the bottle is left open and the resulting release of energy will heat up the solution. Which of the following best describes this type of reaction? | exothermic |
| Which of the following describes what occurs as a gas becomes a liquid? | A physical change occurs; the particles of the gas vibrate more slowly and their kinetic energy decreases. |
| How many liters of fluorine gas can react with 32.0 grams of sodium metal at standard temperature and pressure? Show all of the work used to find your answer. 2Na + F2 2NaF | 32 g Na x (1 mol Na / 23.0 g Na) x (1 mol F2 / 2 mol Na) x (22.4 L / 1 mol F2) = 15.6 L of fluorine 1.5 x 2.0 = 12.0 x V Volume = 0.25 L |
| If 64 grams of O2 gas occupy a volume of 56 liters at a temperature or 25°C, what is the pressure of the gas, in atmospheres (atm)? | 0.87 atm |
| How does the kinetic energy of a substance's particles in the liquid phase compare to their kinetic energy in the gas phase? | The particles have less kinetic energy in the liquid phase than they do in the gas phase. |
| Which of the following best explains what happens when the kinetic energy of particles in a liquid state decreases? | They move more slowly, resulting in the formation of a solid. |
| Which of the following best describes the formation of plasma? | Plasma forms when a gas reaches extremely high temperatures, and electrons are released from the atoms. |
| If you drop a 50 gram piece of metal that has a temperature of 110°Celsius into 1000 grams of water at 25°Celsius, what best describes what would occur? | The water and the metal's temperature will reach the same temperature. |
| Which of the following best describes a chain reaction in a nuclear fission reaction? | The chain reaction continues until all uranium-235 isotopes have split, or until the neutrons fail to collide with any more uranium-235 nuclei. |
| What is the concentration of hydronium ions in a solution with a pH = 3.9? | 1.26 x 10^-4 |
| On a potential energy diagram, what is true about activation energy? | Activation energy is greater for endothermic reactions. |
| How would a system in which both matter and energy are exchanged freely between the system and the surroundings be classified? | an open system |
| Heat from the Earth's core and pressure on the remains of dead plants and animals create which of the following resources | natural gas and coal |
| A laboratory experiment requires 2.0 L of a 1.5 M solution of hydrochloric acid (HCl), but the only available HCl is a 12.0 M stock solution. How could you prepare the solution needed for the lab experiment? Show all the work used to find your answer. | 12 x v2 = 1.5 x 2 V2= .25 Add 1.75 L of H2O to .25 L of 12 M HCl solution to end up with 2.0 L of 1.5 M HCl |
| A laboratory experiment requires 2.0 L of a 1.5 M solution of hydrochloric acid (HCl), but the only available HCl is a 12.0 M stock solution. How could you prepare the solution needed for the lab experiment? Show all the work used to find your answer. | 2000mL(diluted)*1l/1000ml*1.5ml/1L=3 mol 3 mol*1L/12M=.25L 1/4 of a liter of HCl is needed to go with 1.75L of water. |
| What term explains why some materials heat up more quickly than others? | specific heat |
| According to the collision theory and model created to explain the collision theory, what is the best explanation for why a higher temperature makes a reaction go faster? | It increases the average kinetic energy and there are more collisions per minute. |
| Which of the following is the salt in the Brønsted-Lowry neutralization reaction? HBr + NaHCO3 H2CO3 + NaBr | NaBr |
| Which of the following correctly describes a hydrocarbon? | organic compounds that contain only carbon and hydrogen |
| According to the collision theory and model created to explain the collision theory, what happens to a catalyst in a reaction? | it does not get consumed |
| When 13.6 grams of KCl are dissolved in enough water to create a 180-gram solution, what is the solution's concentration, expressed as a percent by mass? | 7.6% KCl |
| Which phase of matter is made up of particles that are packed closely together, with both a definite shape and a definite volume? | solid |
| What does the term organic mean in chemistry? | containing carbon |
| Fuel cell cars that use hydrogen as fuel have the potential to be quiet, produce low emissions, and require less maintenance than gasoline cars. What negative effect might hydrogen fuel have on the environment? | To produce the hydrogen, a fuel must be burned and emissions will be produced. |
| On a potential energy diagram for the following processes, which of the following has a decrease in entropy? | freezing |
| Which of the following describes what occurs as a gas becomes a liquid? | A physical change occurs; the particles of the gas vibrate more slowly and their kinetic energy decreases. |
| On an endothermic potential energy diagram, what is true for all products? | The products are at a higher energy level than the reactants. |
| Describe what happens to the particles of a solid, in terms of movement and kinetic energy, as it is heated to its melting point, including whether this is a physical or chemical change. | The particles in the solid start to speed up as the solid begins to melt. The kinetic energy of the solid that is melting is increased because... |
| Describe what happens to the particles of a solid, in terms of movement and kinetic energy, as it is heated to its melting point, including whether this is a physical or chemical change. | ... the potential energy that the solid had before it started melting is being switched to kinetic energy because the molecules are moving more freely. The melting of a solid is a physical change. |
| A balloon that contains 0.750 moles of gas has a volume of 16.8 L. If the balloon expands to a volume of 25.4 L at a constant pressure and temperature, how many moles of gas would the balloon contain? | 1.13 mol |
| When dissolved in 1000 g of water, which chemical compound will produce a solution with the greatest freezing point depression? | 11 g of calcium fluoride ( CaF2) |
| Consider the following reaction: 2 H2S (g) 2H2 (g) + S 2 (g) Which answer represents the equilibrium constant for this reaction? | [H2]^2x[S2]/[H2S]^2 |
| 15.0g of an unknown substance is heated from 25.0°C to 34.0°C. If 60.6 J of energy is absorbed, identify the unknown substance using the specific heat. | iron |
| Which of the following best describes a chain reaction in a nuclear fission reaction? | The chain reaction continues until all uranium-235 isotopes have split, or until the neutrons fail to collide with any more uranium-235 nuclei. |
| Water is a polar molecule and attracts other polar molecules. Which of the following is a consequence of this property? | Water is considered to be a universal solvent. |
| Which of the following chemical reactions is an oxidation-reduction reaction? | Fe2O3 + 3CO ---->2Fe + 3CO2 |
| Which of the following represents pure water? | [H3O+] = [OH-] |
| Carbon naturally occurs in two forms: diamond and graphite. Why do these two forms have very different properties? | The differences are explained by how the carbon atoms within each substance are covalently bonded together. |
| What is the oxidation number of phosphorus (P) in phosphoric acid (H3PO4)? | +5 |
| If 20.0 mL of a 0.500 M HCl solution is required to neutralize 35.0 mL KOH, what is the concentration of the KOH solution? HCl + KOH KCl + H2O | 0.286 M |
| Which of the following circumstances will result in a reaction that is spontaneous only at high temperatures? | positive enthalpy change and positive entropy change |
| Biotechnology seems to cause much controversy. Why is this field more likely to draw attention from the public? | Its results can greatly improve lives, but sometimes the consequences are negative. |
| A carbon atom has a strong tendency to do which of the following | shares electrons |
| Which of the following is an example of how technology can help protect the environment | compact fluorescent light bulbs |
| Which of the following best describes the forces that generate geothermal power | Heat energy beneath the Earth's surface heats underground water into steam. |
| What is the major problem to overcome before fusion will produce usable energy? | A material able to tolerate the heat must be found. |
| Which of the following describes nuclear fission? | Its chain reactions can be initiated by neutrons |
| Which of the following represents a balanced nuclear equation showing Bismuth-212 undergoing alpha decay followed by beta decay? | 212/83 Bi---->4/2He+208/81Tl---->X- 208/82 Pb +0/-1β |
| Which statement is not correct regarding radiation? | Radioactive elements have an unbalanced number of protons and electrons. |
| Which of the following is not a result when a change to an equilibrium system is applied? | Increasing the rate of the forward reaction will cause a shift to the left. |
| What is the pH of a 0.00750 M solution of hydrochloric acid, HCl? | pH = 2.12 |
| What is the salt formed when magnesium hydroxide reacts with hydrochloric acid? | magnesium chloride |
| Which of the following correctly shows a neutralization reaction between a hydronium ion and a hydroxide ion? | H3O+ + OH- --->2 H2O |
| According to the collision theory and model created to explain the collision theory, why does a catalyst cause a reaction to speed up? | It lowers the activation energy. |
| According to the collision theory and model created to explain the collision theory, what two factors must be satisfied for a given collision to be successful and result in the production of products? | Correct orientation and sufficient energy. |
| On a potential energy diagram for the following processes, which of the following has an increase in entropy? | water freezes |
| Which of the following circumstances will result in a reaction that is spontaneous at all temperatures? | negative enthalpy change and positive entropy change |
| Which of the following reactions results in a decrease in entropy? | CaO (s)+SO3(g)------>CaSO4(s) |
| 125.0 g of an uk sub. is heated to 97.0°C. It is then placed in a calometer than contains 250g of H20 with an initial temperature of 20.0°C. The final temp. is 23.5°C. ? is the specific heat of the uk sub. The specific heat of H20 is 4.18 J/ (°C × g). | 0.398 J/ (°C × g) |
| Which is not true regarding the specific heat of water? | The specific heat of water explains capillary action. |
| On an endothermic potential energy diagram, what is true for all products? | The products are at a higher energy level than the reactants. |
| When sulfuric acid is poured on sugar the volume expands, it turns black and gets very hot. Which of the following best describes this reaction? | exothermic |
| If you drop a 150 gram piece of metal that has a temperature of 125°Celsius into 1000 grams of water at 20°Celsius, what best describes what would occur? | The heat lost by the metal will equal the heat gained by the water. |
| Which of the following solutions will have the greatest colligative effect? | 0.75 moles of calcium fluoride (CaF2) dissolved in 500.0 g of water (H2O) |
| How many grams of potassium nitrate (KNO3) would form if 2.25 liters of a 1.50 molar lead nitrate Pb(NO3)2 solution reacts with 1.15 liters of a 2.75 molar potassium chromate K2CrO4 solution? | 639 g |
| Water molecules move farther apart when water freezes, causing it to expand. Which of the following is a consequence of this property? | The water in lakes and ponds freezes from the top down. |
| Which of the following would be the best technique to use in order to separate an insoluble solid from a liquid? | filtration |
| How many liters of oxygen gas can react with 84.0 grams of lithium metal at standard temperature and pressure? Show all of the work used to find your answer. 4Li + O2 2Li2O (3 points) | There are 12 moles of lithium. and 3 moles of O2. From here you need ideal gas law help to find liters. Standard temperature is 273 and standard pressure is one. Liters formula: V=nRT/P or V= 3*0.0821*273/1=67.24 L |
| When 7.50 L of sulfur trioxide are produced by the reaction of sulfur dioxide in an excess of oxygen at standard temperature and pressure, how many liters of sulfur dioxide were used? 2SO2 (g) + O2 (g) ----> (g) | 7.50L |
| If 1.6 moles of an ideal gas are at a temperature of 25°C and a pressure of 0.91 atm Hg, what volume would the gas occupy, in liters? | 43L |
| A sample of gas has a volume of 3.50 L and a temperature of 298 K. What would be the volume of the same gas sample if the temperature is decreased to 285 K at a constant pressure? | 3.35 L |
| Describe what happens to the particles of a liquid, in terms of movement and kinetic energy, as it is heated to its boiling point, including whether this is a physical or chemical change. | This is a physical change as the only thing changing is the state of matter. The movement and kinetic energy both increase as the particles move faster with higher heat. |
| Which of the following describes what occurs as a solid becomes a liquid? | A physical change occurs; the particles of the solid vibrate faster and their kinetic energy increases. |
| Which phase of matter is made up of particles that are far apart from each other, with both an indefinite shape and an indefinite volume? | gas |
| Which of the following best summarizes the main causes of water pollution today? | leaking septic and sewer systems, manufacturing, farming |
| What would happen if CH4 was removed from the following reaction that has reached equilibrium? CO (g) + 3H2 (g) ----><----CH4 (g) + H2O (g) (2 points) | The equilibrium would shift to the left. |
| Which phase of matter is made up of particles that are packed relatively close together, with an indefinite shape but a definite volume? | liquid |
| When 6.4 grams of LiCl are dissolved in enough water to create a 145-gram solution, what is the solution's concentration, expressed as a percent by mass? | 4.4% LiCl |
| Which of the following best describes the forces that create natural gas? | Heat from the Earth's core and pressure transform the remains of dead plants and animals. |
| Which answer describes a chemical reaction in equilibrium? | The forward and reverse reaction rates are the same. |
| In the chemical reaction shown below, which element was oxidized? 2K + Cl2---> 2KCl | K, because it lost one electron |
| If the half-life of Technitium-104 is 18.0min, how much of a 14.2g sample will remain after 72 minutes? | 0.888 g |
| How many milliliters of a 1.25 molar hydrochloric acid (HCl) solution would be needed to react completely with 60.0 grams of calcium metal? Ca (s) + 2HCl (aq) --->CaCl2 (aq) + H2 (g) | 2400 ml |
| What is the difference between a strong acid and a weak acid? | A strong acid is 100% ionized, a weak acid is less than 100% ionized. |
| Which of the following circumstances will result in a reaction that is spontaneous only at high temperatures? | positive enthalpy change and positive entropy change |
| Which of the following offers the most complete definition of metabolism? | the biochemical reactions that occur in an organism |
| What is the pH of a 6.40 × 10-3 M solution of sodium hydroxide, NaOH? | pH= 11.8 |
| Which of the following describes nuclear fusion? | It involves the combining of nuclei. |
| What is the purpose of environmental remediation? | to remove pollution or contamination from the environment |
| Which of the following reactions results in a decrease in entropy? | 6CO2 (g) + 6H2O (l) ----> C6H12O6 (s) + 6O2 (g) |
| What is the oxidation number of sulfur (S) in magnesium sulfate (MgSO4)? | +6 |
| Describe what happens to the particles of a liquid, in terms of movement and kinetic energy, as it is heated to its boiling point, including whether this is a physical or chemical change. | The particles in a liquid start to speed up when a liquid gets heated up to its boiling point. The KE of the liquid also increases because the potential energy that the liquid had to turn into a gas is being transformed into KE. a physical change. |
| Which of the following would be the best technique to use in order to separate a soluble solid from a liquid? | evaporation |
| When 4.50 L of hydrogen gas react with an excess of nitrogen gas at standard temperature and pressure, how many liters of ammonia gas will be produced? N2 (g) + 3H2 (g)----> 2NH3 (g) | 3.00 L |
| A 5.45g combustible sample is burned in a calorimeter. The heat generated changes the temperature of 555g water from 20.5°C to 39.5°C. How much energy is released by the burning? The specific heat of water is 4.18 J/ (°C × g). | 44100 J |
| If a 12.0g sample of Radon-222 decays so that after 19 days only 0.375g remains, what is the half-life of Radon-222? | 9.5 days |
| If it requires 37.5 mL of a 0.245 M HBr solution to neutralize 18.0 mL Mg(OH)2, what is the concentration of the Mg(OH) 2 solution? 2 HBr + Mg(OH) 2 ---->Mg(Br) 2 + 2 H2O | 0.255M |
| Which of the following chemical reactions is an oxidation-reduction reaction? | NO + 2H2 ----> NH3 + H2O |
| Which of the following best describes the forces that generate solar power? | Energy of the sun strikes photovoltaic cells producing a flow of electrons. |
| Which describes nuclear power plants? | Compared to fossil fuels, they require much less fuel. |
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HannahErin
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