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Questions in chemistry

[Answered] What is the formula for the ionic compound formed by calcium and nitrogen? A. CaN B. [tex]Ca _2 N_3[/tex] C. [tex]Ca _3 N_2[/tex] D. CN

[Answered] $Zn(s) + HCl(aq) \rightarrow ZnCl_2(aq) + H_2(g)$ A piece of zinc is dropped into $0.1 cm^3$ of $0.1 mol \cdot dm ^{-3} HCl$ and the following data were obtained at 4 second intervals. | Time (s) | Mass of zinc (g) | | -------- | ---------------- | | 0 | 0.016 | | 4 | 0.012 | | 8 | 0.010 | | 12 | 0.009 | | 16 | 0.008 | | 20 | 0.008 | 5.1 Calculate the average rate of the reaction for the first 12 s in $mol ^{-1}$. 5.2 Explain why the mass of the zinc remained constant after 16 s. 5.3 Explain how the rate of the reaction changes as time passes. Answer only INCREASES, DECREASES, or REMAINS THE SAME. 5.4 A graph that shows the amount of $H _2$ gas that was produced against time for this reaction is shown below:

[Answered] Fill in the missing information: | symbol | atom or ion? (check all that apply) | number of protons | number of electrons | |---|---|---|---| |$\square$ |$\square$ neutral atom $\square$ cation $\square$ anion | 49 | 47 | | Kr |$\square$ neutral atom $\square$ cation $\square$ anion | $\square$ | $\square$ | | $P ^{2-}$ |$\square$ neutral atom $\square$ cation $\square$ anion | $\square$ | $\square$ |

[Answered] 1. Explain the relationship between photon wavelength and photon energy. Is it proportional or inversely proportional? How do you know? 2. Explain the flame test phenomenon. Why can flame tests be performed? What happens to the electrons in the metal atoms of each compound?

[Answered] Add or subtract the following measurements. Be sure each answer you enter contains the correct number [tex] \begin{aligned} 14.500 g-0.70 g & =\square g \\ 11.570 g-0.8 g & =\square g \\ 15.5 g+1.320 g & =\square g \end{aligned} [/tex]

[Answered] Fill in the missing information: | symbol | | atom or ion? check all that apply | | number of protons | number of electrons | | :----- | :-: | :-------------------------------- | :-: | :---------------- | :---------------- | | 2+ Mg | | cation | | | | | C | | neutral atom | | | | | | | neutral atom | | 51 | 54 |

[Answered] Add or subtract the following measurements. Be sure each answer you enter contains the correct number of significant digits. [tex] \begin{aligned} 14.6 mL+15.50 mL & =\square mL \\ 15.61 mL-5.5 mL & =\square mL \\ 3.520 mL+18.8 mL & =\square mL \end{aligned} [/tex]

[Answered] Complete the table below. For example, in the first row decide whether [tex]$Sc ^{3+}$[/tex] is a cation or anion. In the second row, write the symbol for the ion that an atom of potassium is mostly likely to form and then decide what type of ion it is. | element | most likely ion | |---|---| | | symbol of ion | type of ion | | scandium | [tex]$Sc ^{3+}$[/tex] | | | potassium | | cation | | oxygen | | cation | | barium | | cation | | chlorine | | cation anion

[Answered] Experiments were done on a certain pure substance [tex]$X$[/tex] to determine some of its properties. There's a description of each experiment. In each case, decide whether the property measured was a chemical or physical property of [tex]$X$[/tex], if you can. If you don't have enough information, choose 'can't decide' in the third column. | property | experiment | physical or chemical? | |---|---|---| | D | A sample of [tex]$X$[/tex] is carefully weighed and put inside a vented flask. Water is added to the flask until it just covers the sample, and the volume of sample and water is recorded. Then the sample is removed and the volume of water alone recorded. From the mass of the sample and the difference in volumes, the value of [tex]$D$[/tex] may be calculated. | physical chemical (can't decide) | | 0 | A sample of solid [tex]$X$[/tex] is carefully weighed and put inside a vented flask. The flask is heated until oxygen gas starts being produced. After no more oxygen gas is produced, the contents of the flask are removed and weighed, and from the decrease in weight the value of [tex]$O$[/tex] may be calculated. | physical chemical (can't decide) | | C | A sample of [tex]$X$[/tex] is carefully weighed and put inside a sealed calorimeter. Pure oxygen gas is injected into the calorimeter, and the mixture ignited. After all of [tex]$X$[/tex] has reacted with the oxygen gas, the temperature rise of the calorimeter is measured. From this change in temperature the value of [tex]$C$[/tex] may be calculated. | physical chemical (can't decide) |

[Answered] $33.6 \text{ g}$ of $N_2$ and 24 g of $H_2$ are placed in a $5 \text{ dm}^3$ sealed container and react according to the following balanced equation until dynamic equilibrium is reached. $N_2(g)+3 H_2(g) \rightleftharpoons 2 NH_3(g)$ 6.1 Explain the term "dynamic chemical equilibrium" At 573 K when equilibrium is reached, there is $5.6 \text{ g}$ of $N_2$ gas left inside the container. 6.2 Calculate the concentration of both reactants when the reaction reached equilibrium for the first time. 6.3 Calculate the equilibrium constant $(K_c)$ when this reaction reached equilibrium. 6.4 How would the yield of $NH_3$ change if a smaller container than the $5 \text{ dm}^3$ is used? Write only INCREASES, DECREASES or REMAINS THE SAME. The temperature of this reaction increases from 573 K to 700 K. At this new temperature the equilibrium constant for this reaction decreases. 6.5 Is the forward reaction endothermic or exothermic? 6.6 Explain your answer to QUESTION 6.5.