Química
Reacciones químicas, estequiometría, estructuras moleculares y propiedades.
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multiple-choice question in the h2o molecule, oxygen has a slight _____…
The option with "Oxygen - negative" and "Hydrogen - positive" (the second checkbox option from the left, or the one with those two labels).
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what chemical reaction is represented by the following half - reaction?…
oxidation ### Second Question (Identifying oxidized element)
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which of the following statements is true? oxidation is the loss of ele…
s: First Question:
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fill in the missing number of electrons for each of the following half …
For \(Co^{3+}(aq)+ \square e^-\to Co(s)\), the missing number is \(3\); for \(Na(s)\to Na^{+}(aq)+\square e^-\), the missing number is \(1\).
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the gain of electrons is called blank. when a substance gains electrons…
The gain of electrons is called reduction. For the oxidation state: goes down (decreases)
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given the ionic chemical formulas below, determine oxidation state of t…
| Chemical Formula | Cation Oxidation State | Anion Oxidation State | |------------------|------------------------|-----------------------| | \( NiBr_2 \) | \( +2 \) | \( -1 \) | …
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question 1 what is the oxidation number of the following element? h₂
0
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here we see the valence shells of oxygen and magnesium. how will the el…
D. 2 electrons will move from magnesium to oxygen.
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lets look at how an ionic bond between sodium and chlorine is made. in …
B. Sodium becomes a cation and chlorine becomes an anion.
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lets learn about chemical reactions. in chemistry, atoms are the smalle…
- "These particles have a positive electrical charge" → Proton - "These particles have a negative electrical charge" → Electron - "These particles have no electrical charge" → Neu…
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question 1 which compounds get a phase label of (g)? □ h₂o □ nh₃ □ h₂s …
B. $\ce{NH3}$, C. $\ce{H2S}$, D. $\ce{CO2}$ (Note: Assuming options are labeled as A: $\ce{H2O}$, B: $\ce{NH3}$, C: $\ce{H2S}$, D: $\ce{CO2}$ for clarity. The correct compounds wi…
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question 1 which compounds would get a phase label of (aq)? □ zns □ pbc…
NaCl, Fe(NO₃)₃ (the checkboxes for NaCl and Fe(NO₃)₃ should be selected)
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match phase label to the element barium choose bromine choose (l) (s) (…
- barium: (s) - bromine: (l) - iodine: (s) - nitrogen: (g) - sulfur: (s)
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what are the products when cyclohexane (c₆h₁₂) reacts with elemental ox…
\(CO_2\), \(H_2O\) (corresponding checkboxes for \(CO_2\) and \(H_2O\) should be selected)
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what are product of the reaction of lead(ii) nitrate with sodium chlori…
\(NaNO_3\), \(PbCl_2\) (the checkboxes corresponding to \(NaNO_3\) and \(PbCl_2\) should be selected)
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what is the product of calcium reacting with hydrochloric acid? select …
A. \( \text{H}_2 \), B. \( \text{CaCl}_2 \)
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question 5 3 points how do two hydrogen atoms and one oxygen atom form …
The oxygen atom shares one electron with each of the two hydrogen atoms, forming two covalent bonds (via electron sharing) to create a stable $\ce{H_2O}$ molecule, as this satisfi…
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question 1 what products will form when barium reacts with nitrogen? ○ …
\( \text{Ba}_3\text{N}_2 \) (the option corresponding to \( \text{Ba}_3\text{N}_2 \))
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question 1 select all the combustion reactions. □ fe + o₂ --> co₂ + h₂o…
- \( \boldsymbol{C_3H_8 + 5 O_2 ightarrow 3CO_2 + 4H_2O} \) - \( \boldsymbol{25 O_2 + 2C_8H_{18} ightarrow 18H_2O + 16CO_2} \) (or \(2C_8H_{18} + 25 O_2 ightarrow 16CO_2 + 18H_2O\…
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the reaction system quick check a cold pack is snapped, and the chemica…
This is an endothermic reaction because the system took energy from the surroundings (the third option from the top, or the option with this description).
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match each element to how it behaves when forming a bond. answer choice…
- "Shares 1 electron (covalent)": Hydrogen (H) - "Shares 2 electrons (covalent)": Oxygen (O) - "Transfers 1 electron (ionic)": Sodium (Na) - "Gains 1 electron (ionic)": Chlorine (…
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the reaction system quick check which statement is true of energy in re…
The option "The energy found in the reactants remains in the system, and the reactants also take energy from the surroundings" (the third option in the vertical list of options in…
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question 1 the generic double displacement reactions is ab + cd ---> ad…
B. Cations will not combine with another cation.
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the reaction system quick check a candle slowly burns until the last bi…
The option "In the air, only the oxygen is part of the system." (the third option in the list of choices)
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the generic double displacement reactions is ab + cd ---> ad + cb the a…
C. Cations will not combine with another cation.
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the reaction system quick check which quantity will always have a negat…
C. the change in energy in a system during an exothermic reaction
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the generic single displacement reactions is a + bc ---> ac + b in \int…
D. "C" is an anion and a metal can only become a cation. (assuming the last option is D, if the options were labeled as A, B, C, D with the last option being the correct one as pe…
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question 1 the key to recognizing a decomposition reaction is... ○ ther…
D. there are multiple products and only one reactant.
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question 1 the key to recognizing a combination reaction is... ○ there …
D. there are multiple reactants and only one product.
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select all the reaction types by what the atoms do. ☐ decomposition ☐ d…
- decomposition - double displacement - single displacement - oxidation - combination
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total bond energy quick check hydrogen bromide breaks down into diatomi…
-102 kJ/mol, exothermic (the option with this text, e.g., the second option: \(-102\) kJ/mol, exothermic)
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match the phase label with its meaning. (s) choose (l) choose present o…
(s): present or added as a solid (l): present or added as a liquid (g): present or added as a gas (aq): present or added dissolved in water
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total bond energy quick check how is total reaction energy calculated? …
A. reactant bond energy – product bond energy
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which event is an example of an endothermic reaction? (1 point) photosy…
A. photosynthesis
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which result occurs during an exothermic reaction? (1 point) ○ light or…
A. Light or heat are released into the environment.
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question 1 1 pts when balancing chemical reaction equations, one can ju…
False
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identify the reactants and product in the following chemical reaction e…
- barium hydroxide: reactant - sulfuric acid: reactant - barium sulfate: product - water: product
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molecules 7. one or more atoms that are bonded together are called a 8.…
7. molecule 8. chemical properties Examples: \( \ce{H_2O} \) (water), \( \ce{O_2} \) (oxygen), \( \ce{CO_2} \) (carbon dioxide), \( \ce{CH_4} \) (methane) (any valid molecular com…
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chemical bonds 5. a force that holds atoms together are called b. atoms…
5. Chemical Bonds b. 1. Ionic Bonding 2. Covalent Bonding
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why is choking considered an emergency situation? ○ it may block the fl…
A. It may block the flow of air in the body.
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when a physical change is observed, the composition of the particles th…
True
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practice: element or compound? 1. methane \tch₄ \t______ 2. sulfur \ts₈…
1. Methane (\(CH_4\)): Compound 2. Sulfur (\(S_8\)): Element 3. Hydrogen Peroxide (\(H_2O_2\)): Compound 4. Sulfuric Acid (\(H_2SO_4\)): Compound 5. Ozone (\(O_3\)): Element 6. Ni…
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4. when elements combine to make a compound the new substance has prope…
When elements combine to make a compound the new substance has properties \underline{different} from the original. They may have a new \underline{set of properties} (or other appr…
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1. when elements combine to make a compound the new substance has prope…
First blank: different; Second blank: properties (or other context - appropriate term related to compound properties, but based on standard chemistry, the first is "different" and…
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amelie wants to make her home as safe as possible for her family. which…
C. Test to see whether a carbon monoxide detector works.
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4 when elements combine to make a compound the new substance has proper…
s (Element/Compound): 1. Methane ($\ce{CH4}$): Compound 2. Sulfur ($\ce{S8}$): Element 3. Hydrogen Peroxide ($\ce{H2O2}$): Compound 4. Sulfuric Acid ($\ce{H2SO4}$): Compound 5. Oz…
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we drink water. we breathe out carbon dioxide. we use salt in our foods…
1. Methane: Compound 2. Sulfur: Element 3. Hydrogen Peroxide: Compound 4. Sulfuric Acid: Compound 5. Ozone: Element 6. Nitrous Oxide: Compound
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3. what is a compound? examples: elements that are chemically combined
A compound is a substance formed from two or more different elements that are chemically combined in a fixed proportion. Examples: Water ($H_2O$), Carbon Dioxide ($CO_2$), Sodium …
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what is the new boiling point of a solution prepared by adding 296.0 g …
101.2 \(^\circ\)C (Option: 101.2 \(^\circ\)C)
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when 2.00 moles of a molecular compound was dissolved in 1000. g of wat…
-3.72 °C (corresponding to the option: -3.72 °C)
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a 25.0 ml portion of a 6.00 m nacl solution is used to make 1.00 l of a…
0.150 M
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compounds & formulas we drink water. we breathe out carbon dioxide. we …
These substances (water, carbon dioxide, salt) are all chemical compounds. Water ($H_2O$), carbon dioxide ($CO_2$), and salt (sodium chloride, $NaCl$) are each composed of two or …
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2. what are the two main branches of natural science? physical science …
A. physical science and life science
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sections of the periodic table, showing electron configuration of valen…
B. predicted the existence and properties of undiscovered elements
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question 1 0.5 pts what is the sodium ion concentration (in m) in a 0.3…
1.065 M (corresponding to the option with 1.065 M) ### Question 2
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what is the molality of a solution with 35.5 g c₂h₅oh in 450.0 g water?…
1.71 m
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question 1 how many grams of mgco₃ are in 4.99 l of 0.0851 m mgco₃ solu…
35.8 g (corresponding to the option "35.8 g")
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question 1 a little more difficult problem. what is the molarity of 2.5…
0.0214 M (corresponding to the option "0.0214 M")
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question 1 1 pts determine the mass of solute present in 537 g of aqueo…
18.6g SrCl₂ (the third option: 18.6g SrCl₂)
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what is the correct solution setup for determining the percent by mass …
A. $\% \text{mass} = \frac{775\text{mg NaBr}}{1790\text{mg solution}} \times 100$ (the first option with 1790mg solution in the denominator)
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question 1 match up the solution with its qualitative concentration. 25…
25% KOH solution: concentrated solution 0.15% KOH solution: dilute solution
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question 1 match up the solution with its qualitative concentration. th…
- "There is a visible solid at the bottom of the container." : saturated solution - "If more solute were added, it would dissolve" : unsaturated - "If the solution is bumped or a …
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determining molar mass use the periodic table to calculate the molar ma…
58.33
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m. cobalt (iii) oxide co₂o₃ q. nickel (iii) sulfide ni₂s₃ o. titanium (…
To solve this, we'll go through each row, determining the name from the formula or vice versa using chemical naming rules (ionic, covalent, polyatomic ions, oxidation states). ###…
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in the graph above, notice that the solubility of some compounds is inc…
A. Because HCl, NH₃ and SO₂ are gases and the rest of the compounds are solids.
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an energy profile for a reaction is shown in the diagram. 13 mark for r…
A
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in a third experiment, 0.10 g samples of mg(s) are placed in excess hcl…
B. The reaction time decreases, and the rate of the reaction increases.
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question 1 match the appropriate solvent to use to dissolve the solid. …
solid iodine: liquid cyclohexane (a nonpolar compound) calcium bromide: liquid ammonia
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3. provide the formula for each of the following compounds. a. sodium c…
$Mg(NO_3)_2$ ### Part d: Cesium sulfide
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question 1 1 pts indicate which compounds are soluble in water. □ nano₃…
The soluble compounds are $\ce{NaNO_{3}}$ and $\ce{Li_{2}CO_{3}}$. So the correct checkboxes are for $\ce{NaNO_{3}}$ and $\ce{Li_{2}CO_{3}}$.
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question 1 1 pts when an ionic compound solute dissolves, the particles…
False
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two solid reactants of varying particle size are combined in a vessel. …
D. Temperature = 950° C (with small particle size as per the diagram)
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2 nobr(g) → 2 no(g) + br₂(g) the equation above represents an elementar…
C. Rate = \( k[\text{NOBr}]^2 \)
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the potential energy diagram for the uncatalyzed decomposition of h₂o₂(…
C. Smaller, Unchanged
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select all the statements about gas solutions that are correct. □ gases…
- Gases particles can easily mix because of the large space between the particles. - The amount of each gas present is proportional to each gas’s individual pressure. - The pressu…
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the half-life ($t_{1/2}$) of the catalyzed isomerization of cis-2-buten…
### Part a # Explanation: ## Step1: Recall first-order half-life property For a first - order reaction, the half - life formula is \(t_{1/2}=\frac{\ln2}{k}\), which means that the…
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a two-step reaction mechanism is proposed for a gas-phase reaction, as …
A. The chemical equation for step 1 is \(2NO_2(g) ightarrow NO(g)+NO_3(g)\), and the rate law is \(rate = [NO_2]^2\).
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a worker mixed chemicals that caused a release of toxic gas. in the pas…
D. Inspect the workplace to assess how this happened.
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match the word to its meaning. the process of a solute to move into a s…
1. The process of a solute to move into a solution: Solvation 2. The ability of substance to mix together: Miscibility 3. The ability of a solute to dissolve in a solvent: Solubil…
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step 1: o₃(g) + cl(g) → o₂(g) + clo(g) step 2: clo(g) + o(g) → o₂(g) + …
B. $\ce{Cl(g)}$
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the rate law for the reaction represented above is experimentally deter…
A. Molecular collisions become more frequent.
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select the lewis structure that most accurately represents antimony pen…
The Lewis structure with antimony (Sb) as the central atom, bonded to five chlorine (Cl) atoms (each Cl atom has three lone pairs of electrons) – the bottom - right structure (the…
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select the lewis structure that most accurately represents xenon tetraf…
The second Lewis structure (top - right) with Xe in the center, bonded to four F atoms (two vertically, one top - right, one bottom - right), each F with 3 lone pairs.
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goiter is an enlargement of the thyroid gland in the neck. the most com…
For NaCl: Solvent For NaI: Solute
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select the lewis structure that most accurately represents chlorine pen…
The top - right Lewis structure (the second one in the top row) with Cl bonded to 5 F atoms via single bonds, each F having 3 lone pairs, and Cl having one lone pair.
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select the lewis structure that most accurately represents iodine penta…
The Lewis structure in the top - left box (with I as the central atom, bonded to five Cl atoms, each Cl having three lone pairs) is the correct one.
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step 1: no(g) + o₃(g) → no₂(g) + o₂(g) step 2: no₂(g) + o(g) → no(g) + …
B. a catalyst
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the following graph shows data from an experiment in which no₂(g) decom…
D. The rate law for the reaction is \( \text{rate}=k[\text{NO}_2]^2 \)
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select the lewis structure that most accurately represents sulfur hexaf…
The Lewis structure with S as the central atom, bonded to 6 F atoms (each with 3 lone pairs) (the second structure in the given options).
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2 h₂(g) + 2 no(g) → n₂(g) + 2 h₂o(g) the experimental rate law for the …
B. Step 1: $\boldsymbol{2\ce{NO} ightleftarrows \ce{N_{2}O_{2}}}$ (fast); Step 2: $\boldsymbol{\ce{H_{2} + N_{2}O_{2} -> N_{2}O + H_{2}O}}$ (slow); Step 3: $\boldsymbol{\ce{H_{2} …
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3. why does f not shrink when it gains electrons to form its most commo…
When F gains an electron to form \( F^- \), the number of electrons (10) exceeds the number of protons (9). Electron - electron repulsions in the same valence shell (\( n = 2 \)) …
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step 1: 2 no₂(g) → no₃(g) + no (g) (slow) step 2: no₃(g) + co(g) → no₂(…
B. \(\text{Rate} = k[\text{NO}_2]^2\)
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select the lewis structure that most accurately represents boron trihyd…
The Lewis structure with three single bonds (B in center, three H attached via single bonds, no double bonds or extra lone pairs) – specifically the bottom - left structure (or th…
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if hydrogen gas is collected over water at 20 °c and 763 mm hg, what is…
746 mm Hg
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the reaction represented is first order with respect to \\(\\ce{h2o2}\\…
A. Repeating the experiment with 50. mL of 0.60 M $\ce{H_{2}O_{2}}$ at 300 K
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select the lewis structure that most accurately represents sulfur diflu…
The Lewis structure in the top - right box (the one with central S, single bonds to two F atoms, each F with three lone pairs, and S with two lone pairs: \( \ddot{F}-S-\ddot{F} \)…
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an atmospheric sample is composed of nitrogen, oxygen, argon, and trace…
752 torr (the option: 752 torr)
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select the lewis structure that most accurately represents difluorometh…
The first Lewis structure (with H - C - H, F above and below C, each F with 3 lone pairs, no dots on H)
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an unknown gas occupies a volume of 1250 ml at 26 °c and 705 torr. if t…
50.2 g/mol
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2. when si became the si⁴⁺ ion, did it grow or shrink? which is bigger …
When Si becomes $\text{Si}^{4+}$, it shrinks. Si's atomic radius is bigger than $\text{Si}^{4+}$'s ionic radius.