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Questions in chemistry

[Terjawab] Calculate the number of moles of [tex]CuCl_2 \[.\] 2H_2O[/tex] in a mass of 2.42 g to 3 significant figures.

[Terjawab] Balance the entire chemical reaction using an atom inventory. Remember to balance each element in the reaction. [tex]H_2 O_2 \rightarrow O_2+H_2 O[/tex] What is the coefficient for the water, [tex]H _2 O[/tex], in the balanced equation?

[Terjawab] What's the percent composition of sulfur in [tex]$H _2 SO _4$[/tex]? A) [tex]$2.1 \%$[/tex] B) [tex]$32.7 \%$[/tex] C) [tex]$65.2 \%$[/tex] D) [tex]$98.1 \%$[/tex]

[Terjawab] Two nitro [tex]$\left( NO _2\right)$[/tex] groups are chemically bonded to a patch of surface. They can't move to another location on the surface, but they can rotate (see sketch at right). It turns out that the amount of rotational kinetic energy each [tex]$NO _2$[/tex] group can have is required to be a multiple of [tex]$\varepsilon$[/tex], where [tex]$\varepsilon=1.0 \times 10^{-24} J$[/tex]. In other words, each [tex]$NO _2$[/tex] group could have [tex]$\varepsilon$[/tex] of rotational kinetic energy, or [tex]$2 \varepsilon$[/tex], or [tex]$3 \varepsilon$[/tex], and so forth - but it cannot have just any old amount of rotational kinetic energy. Suppose the total rotational kinetic energy in this system is initially known to be [tex]$12 \varepsilon$[/tex]. Then, some heat is added to the system, and the total rotational kinetic energy rises to [tex]$87 \varepsilon$[/tex]. Calculate the change in entropy. Two rotating [tex]$NO _2$[/tex] bonded to a surfac Round your answer to 3 significant digits, and be sure it has the correct unit symbol.

[Terjawab] Which balances the equation [tex]Mg + O _2 \rightarrow MgO[/tex]? [tex]Mg +2 O _2 \rightarrow 4 MgO[/tex] [tex]2 Mg +2 O _2 \rightarrow 2 MgO[/tex] [tex]2 Mg + O _2 \rightarrow 2 MgO[/tex] [tex]2 Mg +2 O _2 \rightarrow 4 MgO[/tex]

[Terjawab] Fill in the name and empirical formula of each ionic compound that could be formed from the ions in this table: | cation | anion | empirical formula | name of compound | |---|---|---|---| | [tex]Ca ^{2+}[/tex] | [tex]CH _3 CO _2^{-}[/tex] | | | | [tex]K ^{+}[/tex] | [tex]BrO _3^{-}[/tex] | | | | [tex]Na ^{+}[/tex] | [tex]BrO _4^{-}[/tex] | | |

[Terjawab] Solid A + water [$\longrightarrow$] saturated solution At $60^{\circ} C$ 24g + 100g [$\rightarrow$] 124g At $60^{\circ} C$ 100g of water saturate 124g solid 80 g of water saturate? [$=\frac{80g \times 124g}{100g}$]

[Terjawab] Which compound contains only a nonpolar covalent molecule? $O _2$ HCl $H _2 O$ $NO _3$

[Terjawab] - reaction A: Your answer is incorrect. - reaction B: Your answer is incorrect. - reaction C: Your answer Is Incorrect. Use the observations about each chemical reaction in the table below to decide the sign (positive or negative) of the reaction enthalpy [tex]$\Delta H$[/tex] and reaction entropy [tex]$\Delta S$[/tex]. Note: if you have not been given enough information to decide a sign, select the "unknown" option. | reaction | observations | conclusions | |---|---|---| | A | The reverse of this reaction is always spontaneous but proceeds slower at temperatures below [tex]$140 .^{\circ} C$[/tex]. | [tex]$\Delta H$[/tex] is negative [tex]$\Delta S$[/tex] is | | B | This reaction is spontaneous only below [tex]$45 .^{\circ} C$[/tex]. | [tex]$\Delta H$[/tex] is [tex]$\Delta S$[/tex] is | | C | This reaction is slower below [tex]$-3 .^{\circ} C$[/tex] than above. | [tex]$\Delta H$[/tex] is [tex]$\Delta S$[/tex] is |

[Terjawab] Which of the following factors will slow down the rate of reaction? A. Volume reduction B. Increased surface area C. Use as an enzyme D. Decreased temperature