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Questions in chemistry

📝 Answered - A student requires 2.00 L of [tex]$0.100 M NH _4 NO _3$[/tex] from a [tex]$1.75 M NH _4 NO _3$[/tex] stock solution. What is the correct way to get the solution? Use [tex]$M_i V_f=M_f V_f$[/tex]. A. Measure 114 mL of the 1.75 M solution, and dilute it to 1.00 L. B. Measure 114 mL of the 1.75 M solution, and dilute it to 2.00 L. C. Measure 8.75 mL of the 1.75 M solution, and dilute it to 2.00 L. D. Measure 8.75 mL of the 0.100 M solution, and dilute it to 2.00 L.

📝 Answered - A scientist wants to determine how many moles of sodium nitride $(Na_3N)$ could be made from 7.83 mol of nitrogen $(N_2)$. $6 Na+N_2 \rightarrow 2 Na_3 N$ How many moles of sodium nitride could be made?

📝 Answered - Match each group to the correct property. Refer to the periodic table if you need help. alkali metals halogens noble gases solids at room temperature

📝 Answered - Rank these chemical species by increasing pH of an 0.1 M aqueous solution of each. That is, imagine making an 0.1 M solution of each species. Select 1 next to the species that makes the solution with the lowest pH. Select 2 next to the species that makes the solution with the next higher pH, and so on. Notice that some of the rankings have been filled in for you already. Also notice that water is on the list. For that particular case, just compare the pH of pure water to the pH of the other solutions. Note for advanced students: for all charged species, you may assume the necessary counterions act as neither acids nor bases. | species | relative pH of 0.1 M aqueous solution | | :-------------- | :-------------------------------------- | | [tex]$H _3 O ^{+}$[/tex] | 1 (lowest) | | [tex]$C _6 H _5 COOH$[/tex] | -3 | | [tex]$C _6 H _5 COO ^{-}$[/tex] | (Choose one) | | [tex]$HONH _2$[/tex] | 8 (highest) | | [tex]$HONH _3{ }^{+}$[/tex] | (Choose one) | | HCOOH | 2 | | [tex]$HCOO ^{-}$[/tex] | (Choose one) | | [tex]$H _2 O$[/tex] | (Choose one) |

📝 Answered - Which statement best describes a true solution? A. A true solution will settle out after a short period of time. B. A true solution coagulates when heated or boiled. C. A true solution will not separate in a centrifuge. D. A true solution has a cloudy appearance.

📝 Answered - What is the term for the decomposition of a material brought about by heat in the absence of oxygen? A. Pyrolysis B. Conflagration C. Combustion D. Oxidation

📝 Answered - What is the smallest unit of an ionic bond? A. a molecule B. a formula unit C. an atom

📝 Answered - Consider the following data on some weak acids and weak bases: Use this data to rank the following solutions in order of increasing pH. In other words, select a '1' next to the solution that will have the lowest pH, a '2 the solution that will have the next lowest pH, and so on.

📝 Answered - Type the correct answer in the box. The solubility of calcium carbonate is [tex]$14 \frac{\text { milligrams }}{\text { liter }}$[/tex]. 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.

📝 Answered - A. 125.6 kJ B. 3440 kJ C. 1720 kJ D. 10.4 kJ