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Questions in chemistry

[Terjawab] The preparations of two aqueous solutions are described in the table below. For each solution, write the chemical formulas of the major species present at equilibrium. You can leave out water itself. Write the chemical formulas of the species that will act as acids in the 'acids' row, the formulas of the species that will act as bases in the 'bases' row, and the formulas of the species that will act as neither acids nor bases in the 'other' row. You will find it useful to keep in mind that [tex]$NH _3$[/tex] is a weak base. | 0.9 mol of HBr is added to 1.0 L of a [tex]$0.9 M NH _3$[/tex] solution. | acids: $\square$ bases: $\square$ other: $\square$ | | 0.41 mol of KOH is added to 1.0 L of a solution that is 1.5 M in both [tex]$NH _3$[/tex] and [tex]$NH _4 Br$[/tex]. | acids: $\square$ bases: $\square$ other: $\square$ |

[Terjawab] A sample of tin ($Cp = 0.227 J / g \cdot{ }^{\circ} C$) is placed in a freezer. Its temperature decreases from $15.0^{\circ} C$ to $-10.0^{\circ} C$ as it releases 543 J of energy. What is the mass of the sample? Round your answer to three significant figures. Use the formula $q=m C_y \Delta T$. $\square$ g

[Terjawab] An electric device delivers a current of [tex]$15.0 A$[/tex] for 30 seconds. How many electrons flow through it?

[Terjawab] Draw the Lewis structure for the hypochlorite ion, [tex]$ClO^{-}$[/tex]. Include lone pairs and formal charges.

[Terjawab] Type the correct answer in the box. The solubility of calcium carbonate is $14 \frac{\text { milligrams }}{\text { liter }}$. This rate means that 14 milligrams of calcium carbonate can dissolve in 1 liter of water. How much water would be required to fully dissolve 11 grams of calcium carbonate? Express your answer to the correct number of significant figures. One milligram is equal to 0.001 grams. It would take $\square$ liters of water to fully dissolve 11 grams of calcium carbonate.

[Terjawab] Calculate the pH at [tex]$25^{\circ} C$[/tex] of a 0.58 M solution of pyridinlum chloride [tex]$\left( C _5 H _5 NHCl \right)$[/tex]. Note that pyridine [tex]$\left( C _5 H _5 N\right)$[/tex] is a weak base with a [tex]$pK_b$[/tex] of 8.77. Round your answer to 1 decimal place.

[Terjawab] James Chadwick’s experiment in 1932 provided evidence for the existence of _______ within the nucleus

[Terjawab] Calculate the pH at $25^{\circ} C$ of a 0.68 M solution of sodium propionate $\left( NaC _2 H _5 CO _2\right)$. Note that propionic acid $\left( HC _2 H _5 CO _2\right)$ is a weak acid with a $p K_a$ of 4.89. Round your answer to 1 decimal place. $pH=$

[Terjawab] Consider the following system at equilibrium. [tex]CaCO_3(s) \Leftrightarrow Ca^{2+}(aq)+CO_3^{2-}(aq)[/tex] The addition of which compound will cause a shift in equilibrium because of a common ion effect? A. [tex]CCl _4[/tex] B. [tex]CO _2[/tex] C. [tex]CuSO _4[/tex] D. [tex]Na _2 CO _3[/tex]

[Terjawab] What is k in the rate law equation? Rate=k[A][B] A. A pressure constant B. A volume constant C. A rate constant D. An equilibrium constant