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Questions in chemistry

[Answered] 12. Which of the following occur during the electrolysis of dilute H₂SO₄? A. The overall reaction is: H₂(g) + ½ O₂(g) → H₂O(g) B. SO₄²⁻ is discharged at the anode. C. A basic solution is formed. D. H⁺ is discharged at the negative electrode. 13. In an activity during laboratory session a small amount of lead bromide (PbBr₂) crystals were placed in a beaker. Two electrodes are inserted until they are in contact with the PbBr₂ crystals. When the PbBr₂ crystals in the beaker are gently heated, which of the following will be observed? A. Bromide ion is oxidized at the cathode. B. Bromine gas is evolved at the anode. C. Lead (II) ion is oxidized at the cathode. D. Lead (II) ion is reduced at the anode. 14. What is the name given to the pollution caused by the dumping of non-biodegradable wastes into the environment? A. Land pollution B. Air pollution C. Water pollution D. Sound pollution 15. What is the purpose of the conversion of pig iron to steel? A. To remove impurities by reduction. B. To remove impurities by oxidation. C. To decrease the concentration of iron in the pig iron. D. To increase the concentration of iron in the pig iron. 16. Which of the following statements CORRECTLY describes the law of conservation of mass? A. Mass is neither created nor destroyed during a chemical reaction. B. The total mass of substances varies during a chemical reaction. C. Pure compounds always contain the elements in the same percentage by mass. D. A particular compound is composed of the same elements in the same parts by mass.

[Answered] Sulfur reacts with oxygen to form sulfur dioxide ($SO_2(g), \Delta H_{f}=-296.8 \text{ kJ/mol}$) according to the equation below: $S(s)+O_2(g) \rightarrow SO_2(g)$ What is the enthalpy change for the reaction? Use $\Delta H_{\text{rxn}} = \sum(\Delta H_{\text{f,products}}) - \sum(\Delta H_{\text{f,reactants}})$ A. -593.6 kJ B. -296.8 kJ C. 296.8 kJ D. 593.6 kJ

[Answered] 1. From the following ionic equations below, put a tick (✓) if there is a reaction taking place and a cross (X) if there is no reaction taking place. a. [tex]Zn ^{2+}( aq )+ Fe ( s ) \longrightarrow Fe ^{2+}(\frac{ aq }{ a })+ Zn ( s )[/tex] b. [tex]Mg ^{2+}( aq )+ Zn ( s ) \longrightarrow Zn ^{2+}( aq )+ Mg ( s )[/tex] c. [tex]Fe ^{2+}( aq )+ Zn ( s ) \longrightarrow Zn ^{2+}( aq )+ Fe ( s )[/tex] d. [tex]Pn ^{2+}( aq )+ Cu ( s ) \longrightarrow Cu ^{2+}( aqu ) ! Pu ( s )[/tex] e. [tex]Cu ^{2+}( aq )+ Fe ( s ) \longrightarrow Fe ^{2+}( aq )+ Cu ( s )[/tex] 2. Define spectator ion

[Answered] The Lewis structures of four compounds are given. O=S=O O=C=O H-C(Cl)H-Cl Cl-P(Cl)-Cl Which of these molecules are polar? SO2 PCl3

[Answered] Scenario: You are testing two different household solutions with your cabbage indicator, using the color key to the right. Cabbage pH Indicator Color Key \begin{tabular}{l|l|l|l|l|}\0-2 & 3-4 & 5-6 & 7 & 8-9 \ \ \hline \end{tabular} Using the results from the two previous questions: Solution One: [tex]$1 \times 10^{-8} M$[/tex] Solution Two: [tex]$1 \times 10^{-7} M$[/tex] The hydrogen ion concentration of these two solutions differ from each other by a factor of

[Answered] Propane $(C_3 H_8(g), \Delta H_{ f }=-103.8 kJ / mol)$ reacts with oxygen to produce carbon dioxide $(CO_2, \Delta H_{ f }=-393.5 kJ / mol)$ and water ($H_2 O , \Delta H_f=-241.82 kJ / mol$) according to the equation below. $C_3 H_8(g)+5 O_2(g) \rightarrow 3 CO_2(g)+4 H_2 O(g)$ What is the enthalpy of combustion (per mole) of $C_3 H_8(g)$ ? Use $\Delta H_{\text {pxn }}=\sum(\Delta H_{\text {t, products }})-\sum(\Delta H_{\text {t, reactants }})$. A. $-2,044.0 kJ / mol$ B. $-531.5 kJ / mol$ C. $531.5 kJ / mol$ D. $2,044.0 kJ / mol$

[Answered] What do the arrows represent? Solid <--> Liquid <--> Gas

[Answered] 6. Chromatography and fractional distillation can be used to separate. In which type of separation is a thermometer needed for checking that complete separation has occurred? A) Chromatographic separation of two colourless solids B) Chromatographic separation of two solids of different colours C) Fractional distillation of two colourless solids D) Fractional distillation of two solids of different colours

[Answered] $Fe_2 O_3+3 H_2 O \rightarrow 2 Fe(OH)_3$ The molar mass of each substance is provided in the table below. | Substance | Molar Mass (g/mol) | | :-------------------------------------------------- | :------------- | | Iron (III) oxide $\left( Fe _2 O _3\right)$ | 159.70 | | Water $\left( H _2 O \right)$ | 18.02 | | Iron $($ III $)$ hydroxide $\left( Fe ( OH )_3\right)$ | 106.87 | How many moles of water are needed?

[Answered] Regarding the formula $Al_2 O_3$, which of the following is accurate? A) The chemical symbol Al indicates that argon is present in the substance. B) The subscript 2 indicates that two atoms of aluminum are present in the substance. C) The coefficient 3 indicates that there are a total of three atoms of oxygen present in the substance. D) The subscript 2 indicates that two atoms of oxygen are present in the substance.