IdeasCuriosas - Every Question Deserves an Answer Logo

Questions in chemistry

[Answered] Explain the process of formation of a molecule of ammonia, sodium chloride, and magnesium chloride with figures.

[Answered] A student sets up the following equation to solve a problem in solution stoichiometry. (The ? stands for a number the student is going to calculate.) Enter the units of the student's answer. [tex]\frac{(0.27 L)\left(\frac{1 mL}{10^{-3} L}\right)\left(2.07 \frac{g}{mL}\right)}{\left(20.15 \frac{g}{mol}\right)}=? \square[/tex]

[Answered] What transition energy corresponds to an absorption line at 527 nm? A. $2.65 x 10^{-19} J$ B. $5.69 x 10^{-19} J$ C. $3.77 x 10^{-19} J$ D. $3.26 x 10^{-19} J

[Answered] Consider the chemical equations shown here. [tex] \begin{array}{l} 2 H_2(g)+O_2(g) \rightarrow 2 H_2 O(g) \Delta H_1=-483.6 kJ \div 2=-241.8 kJ / mol \\ 3 O_2(g) \rightarrow 2 O_3(g) \Delta H_2=284.6 kJ+2=142.3 kJ / mol \end{array} [/tex] What is the overall enthalpy of reaction for the equation shown below? [tex]$3 H_2(g)+O_3(g) \rightarrow 3 H_2 O(g)$[/tex]

[Answered] Consider the following intermediate chemical equations: [tex]$\begin{array}{l} 2 Na(s)+Cl 2(g) \rightarrow 2 NaCl(s) \ 2 Na_2 O(s) \rightarrow 4 Na(s)+O_2(g) \end{array}$[/tex] In the final chemical equation, NaCl and [tex]$O _2$[/tex] are the products that are formed through the reaction between [tex]$Na _2 O$[/tex] and [tex]$Cl _2$[/tex]. Before you can add these intermediate chemical equations, you need to alter them by A. multiplying the second equation by 2. B. multiplying the first equation by 2. C. multiplying the first equation by (1/2). D. multiplying the second equation by (1/4).

[Answered] What is the frequency of a photon with an energy of 4.56 $10^{-19} J$? A. $6.42 x 10^{14} Hz$ B. $5.10 x 10^{14} Hz$ C. $6.88 x 10^{14} Hz$ D. $4.36 x 10^{14} Hz

[Answered] Consider the following intermediate chemical equations: [tex] \begin{array}{l} 2 Na(s)+Cl(g) \rightarrow 2 NaCl(s) \ 2 Na_2 O(s) \rightarrow 4 Na(s)+O_2(g) \end{array} [/tex] In the final chemical equation, NaCl and [tex]O _2[/tex] are the products that are formed through the reaction between [tex]Na _2 O[/tex] and [tex]Cl _2[/tex]. Before you can add these intermediate chemical equations, you need to alter them by A. multiplying the second equation by 2. B. multiplying the first equation by 2. C. multiplying the first equation by (1/2). D. multiplying the second equation by (1/4).

[Answered] Why do we say that a chemical change results in the formation of new substances? Give an example to illustrate your point.

[Answered] Consider the following intermediate chemical equations: [tex]\begin{array}{ll} CH_4(g) \rightarrow C(s)+2 H_2(g) & \Delta H_1=74.6 kJ \\ CCl_4(g) \rightarrow C(s)+2 Cl_2(g) & \Delta H_2=95.7 kJ \\ H_2(g)+Cl_2(g) \rightarrow 2 HCl(g) & \Delta H_3=-92.3 kJ \end{array}[/tex] What is the enthalpy of the overall chemical reaction [tex]CH _4(g)+4 Cl _2(g) \rightarrow CCl _4(g)+4 HCl ( g )[/tex]? A. -205.7 kJ B. -113.4 kJ C. -14.3 kJ D. 78.0 kJ

[Answered] Select the best answer for the question. 4. What happens to a substance at critical temperatures? A. The substance changes its state if it continues gaining or losing thermal energy B. The substance can't lose any more thermal energy. C. The substance can't change its state, only its temperature. D. The substance changes its state only if it gains thermal energy.