Chem Quiz/Test – Flashcards
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Chemical Kinetics
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The study of reaction rates
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Reaction Rate refers to...
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how quickly or slowly the reactants disappear and the products appear. It is measured in terms of the change in concentration of the reactants.
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If a reaction is to occur, reacting particles must first
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COLLIDE and and this collision must be effective.
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What are the two characteristics of an effective collision?
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*Sufficient energy *Correct orientation
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What are the five major factors that affect reaction rate?
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a) temperature (speed) b) pressure (in gases) c) concentration of reactants d) surface area (particle area) e) presence of a catalyst
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Why would a mixture of gases react faster when the volume they occupy is decreased?
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Because there is more pressure and the concentration increases, which creates more collisions, which creates a faster reaction rate.
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Why would iron filings rust faster than an iron nail?
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more surface area--> more collisions--> faster reaction
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What is the effect of a catalyst on the required energy to achieve effective collisions?
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Catalyst lowers the energy needed for an effective collision. (Activation energy)
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Enzymes act as WHAT?
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CATALYSTS in our bodies
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Have you ever noticed that your hands seem to get stiff when they get cold? Well, the reason behind this is...
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these enzyme reactions causing the muscles to contract slow down when your hands are cold so you can't contract your muscles as fast and your hands feel stiff!
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Decreasing temperature...does what to the rate of the reaction?
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decreases the rate of the reaction
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Enzymes are in molds and bacteria that spoil food. Explain why food doesn't spoil as fast when it is refrigerated as it would at room temperature.
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Because of the lowered temperature, there are less collisions, which slows down the reaction!
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Due to decomposition reactions with oxygen or carbon dioxide in the air, meat begins to feel slimy and smell spoiled. Explain, why meat spoils less rapidly when left unsliced.
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Because when it is unsliced, there is less surface area, which means less collisions, which slow down the reaction.
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Why is there a danger of explosions in places such as silos and coal mines where there are large quantities of powered, combustible materials?
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High concentration + high surface area---> faster reactions
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How do you tell if a graph is endothermic?
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It's endothermic if the products have higher energy than the reactants.
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How do to find activation energy?
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Activated complex-reactions= Act. energy
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Nucleon
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what is inside of nucleus, like protons and neutrons
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Isotope
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an element with a diff number of electrons
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Strong Force
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because protons repel each other, neutrons are used to attract protons so the particle can stay in tact...Strong Force is not well understood.
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Mass Defect
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Mass can be converted into energy; E=mc^2
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Band of Stability
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...
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Radioactivity
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...
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Fission
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atoms splitting
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Fussion
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atoms coming together
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Alpha description
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2 protons/ 2 neutrons, charge: 2 power: small
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Beta description
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electron; charge: -1 power: medium
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Gamma des
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ER, charge: 0, power: large
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If an isotope undergoes decay, the radioactive particle is located on the ___________ side of the equation. If an isotope is bombarded, the radioactive particle is located on the ________ side of the equation.
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*Right or product *Left or reactant
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Alpha decay:
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particle emitted: 4 2 He change in mass number: -4 change in atomic number: -2
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Beta decay:
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particle emitted: 0 -1 e change in mass number: 0 change in atomic number: +1
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Positron emission (decay)
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particle emitted: 0 +1 e change in mass number: 0 change in atomic number: -1
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Gamma emission (decay)
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particle emitted: 0 0 [gamma symbol/upside- down fish] change in mass number: 0 change in atomic number: 0
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Nuclear Reaction vs. Normal Chemical Changes
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-Nuclear reactions involve the nucleus -The nucleus opens, and protons and neutrons are rearranged -The opening of the nucleus releases a tremendous amount of energy that holds the nucleus together---called binding energy -Normal CHEM reactions involve electrons, not protons and neutrons
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n/p ratios for atomic #'s 2-30 is... n/p ratios for atomic #'s greater than 30 is...
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a) 1 b) 1.5
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alpha
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positively charged helium isotope
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gamma
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is pure energy; called a ray rather than a particle is deadly
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Neutron description positron description proton description
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a) 1 0 n = neutron b) [a positive electron] 0 +1 e c) proton/hydrogen-1 1 1 H
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What is ER?
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ER = electromagnetic radiation + electron moves from a higher energy level to a lower one
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What type of radiation can damage DNA?
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gamma
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What is the name of the woman who was a pioneer of nuclear chemistry?
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MARIE CURIE
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What makes the mass of C-12 and C-14 diff?
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The number of neutrons C-12 has 5; C-14 has 8
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hyphen notation for the following: atomic number of 11 and mass number 23
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23-Na
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nuclear symbol for atomic no. 11 and mass 23
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23 11 Na
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Three types of nuclear radiation?
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alpha, beta, gamma
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What type of nuclear radiation has the largest mass?
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alpha
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What type of nuclear radiation has the smallest mass?
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gamma
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Radioactive decay
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The spontaneous break-down of a nucleus into a slightly lighter nucleus, accompanied by the emission of nuclear radiation.
