化学
化学反应、化学计量、分子结构与元素性质。
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question 13 of 30 the reaction below shows how the potential energy cha…
B. The red arrow shows that enthalpy is negative, indicating an exothermic reaction.
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question 12 of 30 for a reaction, $\\delta h = 198$ kj. for which value…
A. 396 kJ
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question 11 of 30 the enthalpy of a reaction is -1207 kj/mol. which of …
B. Exothermic
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question 9 of 14 determine the empirical formula for the compound with …
$\ce{C_{5}H_{4}}$ ### For the compound with molecular formula $\boldsymbol{\ce{H_{2}S_{2}O_{8}}}$:
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question 10 of 30 during a reaction, the enthalpy of formation of an in…
B. 180.6 kJ
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which of the elements are nonmetals? manganese iodine mercury carbon si…
iodine, carbon, selenium (the checkboxes for these elements should be selected)
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ailanthus mel-con conclusion we will use the mel-con format in this cla…
The amount of allelopathic chemicals varies in different parts of the Ailanthus plant.
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question 9 of 30 what is the change in enthalpy of the first reaction b…
C. -112 kJ
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15. the activation energy needed for a chemical reaction is determined …
A. reactant (assuming the first option is "reactant" with a typo, as the text shows "reactant" - like spelling error but contextually, activation energy is determined by reactants…
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select the pair of elements you would expect to have similar properties…
B. P and N
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question 8 of 30 for a reaction, $\\delta h^0 = 176\\ \\text{kj/mol}$ a…
B. \( T> 617\space K \)
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why is the atomic mass of iron, 55.845 amu, most similar to the mass of…
The atomic mass is the weighted average of the masses of all of the isotopes. Iron - 56 is the most abundant isotope, so the atomic mass of iron is most similar to the mass of iro…
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below boundary (safe) zone of uncertainty (increasing risk) beyond zone…
To solve this, we analyze each environmental issue based on planetary boundaries (scientific consensus on safe, uncertain, high - risk zones): ### Below boundary (safe) - **biogeo…
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question 7 of 30 what is the relationship between the enthalpy (δh) and…
C. $-\Delta H, +\Delta S$
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question 6 of 30 the diagram below shows how the potential energy chang…
D. The reaction is exothermic because the reactants are higher in energy than the products.
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question 4 of 30 the temperature of 500 ml of water is 16⁰c. what happe…
B. The temperature of the water increases because the average kinetic energy of the water molecules increases.
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8. the amount of energy needed for a reaction to occur is called (1 poi…
D. activation energy
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question 6 of 14 iron has four naturally occuring isotopes: iron-54, ir…
D. iron - 58 ### Second Sub - Question: Identify the most abundant isotope
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question 3 of 30 what is the best definition of the enthalpy of formati…
D. The energy required for a molecule to form from its elements
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what information cannot be identified if the number of protons for a ne…
number of neutrons
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what does a positive value of $\\delta g^0$ mean for a reaction? a. the…
C. The reaction is nonspontaneous.
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question 1 of 30 what does hesss law state about the total enthalpy cha…
B. It is independent of the reaction pathway.
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question 4 of 14 write the nuclear symbol for the neutral atom shown. n…
\( \ce{^{24}_{12}Mg} \)
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4. chemical reactions and enzymes - match the following term to the cor…
- Activation Energy: b. The amount of energy that needs to be absorbed for a chemical reaction to start. - Catalyst: e. A substance that decreases the activation energy needed to …
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what is the conjugate acid of hso₄⁻ in the reaction below? h₂so₄(aq) + …
D. \( \text{H}_2\text{SO}_4 \)
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classify each statement about subatomic particles as true or false. tru…
To solve this, we analyze each statement based on subatomic particle properties: ### 1. "Protons and electrons have approximately the same mass." - Protons have a mass of ~\(1.67 …
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1. chemical reactions that absorb more energy than they release are cal…
B. Endothermic (assuming the options are labeled with B for endothermic as per typical multiple - choice setups; adjust label if needed based on actual option numbering)
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question 31 of 32 which factor(s) will most likely lower the activation…
D. Catalysts
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1. what element is present in all organic molecules? (1 point) ○ carbon…
A. Carbon.
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how do changes in temperature affect the rate of a reaction? a. changin…
C. Increasing temperature increases the reaction rate because the particles move faster and collide more often.
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which of the following is a property of both acids and bases? a. they f…
A. They form solutions that conduct electricity.
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question 28 of 32 how does the rate of a reaction change after a cataly…
C. The rate increases.
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determine which statements are consistent with daltons atomic theory. c…
Consistent: - All matter is made of atoms; atoms cannot be divided or destroyed. - Atoms of one element cannot be converted into atoms of another element. - Chemical reactions com…
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the ph of a carbonated drink is 3.0. what is the hydrogen ion concentra…
D. $1\times 10^{-3}\ M$
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carbon can react with hydrogen to form several different compounds. two…
The mass ratio of carbon to hydrogen in methane is 3:1. The mass ratio of carbon to hydrogen in ethylene is 6:1.
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question 26 of 32 the table below gives the equilibrium concentrations …
D. \( 1.7\times 10^{-3} \)
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which compound is a base? ○ a. hcn ○ b. naf ○ c. (ce{ca(oh)2}) ○ d. (ce…
C. $\ce{Ca(OH)2}$
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question 24 of 32 which of the following tends to decrease the rate of …
A. Using a less concentrated reaction mixture, C. Using larger particles of the solid reactant
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question 23 of 32 the equilibrium concentrations for the reaction betwe…
D. \( K = 1.3 \times 10^4 \); product favored
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question 22 of 32 a solution of ammonia nh₃(aq) is at equilibrium. how …
C. $[\ce{NH_{4}^{+}}]$ and $[\ce{H^{+}}]$ would decrease.
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question 21 of 32 the acid dissociation constant, ( k_a ), of ( \text{h…
C. \( \ce{HNO_3} \) is a weak acid.
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a mixture of reactants and products for the reaction shown below is at …
B. More \( \ce{NH3} \) would be produced until a new equilibrium position was reached.
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question 19 of 32 a solution of carbonic acid, h₂co₃(aq), is at equilib…
D. More \(H^+\) and \(HCO_3^-\) would be produced.
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question 18 of 32 which of the following increases the h⁺ concentration…
C. An acid
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the ph of a solution is measured as 4.5. what is the hydrogen ion conce…
A. $3.2\times 10^{-5}\ M$
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arrange the steps for determining the density of the metal slugs using …
First step: Weigh and record the mass of a clean 50 mL graduated cylinder. Second step: Add between 15 mL and 20 mL of water to the graduated cylinder. Record the volume of water …
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what does the red line in the diagram below represent? diagram: potenti…
C. The potential energy of the reactants
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question 15 of 32 what is the equilibrium expression for the reaction b…
A. \(\frac{[\text{CO}_2]}{[\text{O}_2]}\)
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question 14 of 32 the reaction below is at equilibrium. what would happ…
B. The equilibrium position would remain the same.
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what is the ph of a $1.0 \\times 10^{-4} m$ koh solution? $\\bigcirc$ a…
A. 10
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arrange the steps for determining the density of a liquid using a gradu…
First step: Weigh and record the mass of a clean 50 mL beaker. Second step: Measure 5.0 mL of the liquid in a 10 mL graduated cylinder. Third step: Pour the liquid from the gradua…
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question 12 of 32 what is the equation for the acid dissociation consta…
C. \( K_{a} = \frac{[\text{H}_3\text{O}^+][\text{F}^-]}{[\text{HF}]} \)
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when determining the density of acetone, you measure out several aliquo…
5
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question 11 of 32 which statement best describes a weak base in solutio…
C. The base dissociates slightly.
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question 11 of 11 when determining the density of acetone, you measure …
10
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question 10 of 32 solution a has a ph of 7, and solution b has a ph of …
C. Solution B is basic, and solution A is neutral.
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question 7 of 11 select the extensive physical property. volume boiling…
A. volume
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how are the concentration of the reactants and reaction rate related? a…
C. A change in concentration results in a change in the rate of a reaction.
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question 8 of 32 some vitamins and dietary supplements are stored in op…
B. Catalyst
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what is the density of a slug of tin that weighs 32.0320 g and occupies…
\( 7.28 \)
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what is the value of the volume of the liquid in the graduated cylinder…
76
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question 7 of 32 what would happen if a small amount of acid were added…
A. The pH would remain about the same.
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question 6 of 32 which of the following combinations of compounds will …
B. $\ce{CH3COOH}$ and $\ce{NaCH3COO}$
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question 5 of 32 what is the equilibrium expression for the reaction be…
A. \(\frac{[\ce{NH3}]^2}{[\ce{N2}][\ce{H2}]^3}\)
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question 4 of 32 how would the graph below change if a catalyst were ad…
B. Part 2 would be lower, and parts 1 and 3 would be unchanged.
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question 3 of 32 how would the equilibrium of the reaction below be aff…
C. The concentrations of \( \ce{O_{2}} \) and \( \ce{SO_{2}} \) would increase.
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question 2 of 32 what are the products of the neutralization reaction b…
C. CaCl₂ and H₂O
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question 1 of 32 hydrogen and oxygen react to form water. which stateme…
B. The concentrations of water, oxygen, and hydrogen are stable.
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at room temperature (20 °c), liquid water has a density of 1.00 g/ml an…
First blank: is less dense than; Second blank: float
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carbon compounds quick check which structure defines the sulfhydryl fun…
A. SH
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carbon compounds quick check which type of bonds can carbon atoms form …
C. single, double, and triple bonds
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carbon compounds quick check which option describes the structure of th…
B. The inner shell is complete with two electrons. The outer shell is incomplete with four electrons.
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carbon compounds quick check why is carbon said to provide a \backbone\…
D. Carbon atoms can form chains and branches with each other, and other atoms can attach to these.
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question 29 of 30 what happens to ice as it melts? a. the released ener…
C. The absorbed energy breaks apart intermolecular forces.
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arrange the following substances from least dense to most dense. most d…
Least dense: methanol (\( d = 0.792 \, \text{g/mL} \)) → water (\( d = 0.998 \, \text{g/mL} \)) → magnesium (\( d = 1.74 \, \text{g/mL} \)) → iron (\( d = 7.87 \, \text{g/mL} \)) …
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question 28 of 30 how many moles of neon (ne) gas have a volume of 0.84…
D. 0.21 mol
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question 27 of 30 which method can be used to separate a mixture of eth…
C. Distillation
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a scientist is working with methane (ch₄) and butane (c₄h₁₀). which sta…
C. They are compounds made of the same two elements, but each contain different numbers of atoms.
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question 27 of 30 which method can be used to separate a mixture of eth…
C. Distillation
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question 26 of 30 how do forces between particles in gases compare to f…
D. The forces in gases are weaker than forces in solids and liquids.
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question 25 of 30 when sugar is added to a sugar solution, the sugar di…
B. Unsaturated
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question 23 of 30 which statement best describes the intermolecular for…
B. Van der Waals forces are the strongest force between \( \ce{H_2} \) molecules, and hydrogen bonding is the strongest force between the \( \ce{NH_3} \) molecules.
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4. hearing protection should be worn anytime the noise level exceeds a.…
d. 90 dB ### Question 5
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question 22 of 30 with carbon dioxide, what phase change takes place wh…
C. A liquid changes to a solid.
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question 21 of 30 the partial pressures of the gases in a mixture are 0…
C. 2.76 atm
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question 20 of 30 which solution is an example of a nonelectrolyte? a. …
A. Iodine in hexane
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if an atom has 4 protons, 3 neutrons and 4 electrons, then this is an a…
beryllium (the option corresponding to beryllium, e.g., if the options are as given: the option with "beryllium")
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question 18 of 30 what is the change in the freezing point of water whe…
A. -0.634$^\circ$C
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central part of the atom containing protons and neutrons * 1 point drop…
atom
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question 17 of 30 what is the phase of water at 0.25 atm and 0°c? phase…
D. Solid
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question 16 of 30 what is the predicted change in the boiling point of …
C. \( 0.015^\circ C \)
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question 15 of 30 charless law describes the relationship of the volume…
C. The volume would be 3/4 of its original value.
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question 10 of 10 suppose a sample of water in this experiment had a ma…
### Conversion to pounds (lb) # Explanation: ## Step1: Identify conversion factor We know that \( 1\ \text{lb} = 454\ \text{g} \), so the conversion factor to convert grams to pou…
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question 13 of 30 in diamond, carbon atoms are bonded together by exten…
A. Network
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when your workplace obtains new materials, you should add them to the c…
C. Immediately
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the hazard communication standard requires employers to do all of the f…
A. Prepare and post a list of all employees who handle hazardous and toxic substances in the workplace
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suppose a buret was used to deliver 18.77 ml of water into a beaker. ex…
s: - \(18.77\space mL=\boldsymbol{0.01877}\space L\) - \(18.77\space mL=\boldsymbol{1.877\times 10^{4}}\space\mu L\) (If we consider the box with \(×10^{0}\), there might be a mis…
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question 10 5 points using your data table 1 step 2, from your procedur…
11.8 ### Question 11 (Note: Since no data table is provided, we can't calculate the exact values, but here's the method for each part): #### Part a: To find the initial volume of …
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question 11 of 30 avogadro’s law relates the volume of a gas to the num…
A. 4 moles gaseous product
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which of the following is a characteristic of solid silver? a. high ele…
A. High electrical conductivity