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Questions in chemistry

[Terjawab] 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).

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

[Terjawab] 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

[Terjawab] 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.

[Terjawab] Do every acrylic hat use –CH₂–CH(CN)–?

[Terjawab] Consider the equations below. [tex]\begin{array}{c} H_2 \rightarrow 2 H \\ C_2 H_4+H \rightarrow C_2 H_5 \\ C_2 H_5+H \rightarrow C_2 H_6 \end{array}[/tex] When these equations are added together, what will the overall equation be? Assume that no equations need to be reversed. [tex]C _2 H _4+ H _2 \rightarrow C _2 H _6[/tex] [tex]H _2+ C _2 H _4+2 H + C _2 H _5+\rightarrow 2 H + C _2 H _5+ C _2 H _6[/tex] [tex]C _2 H _4+ C _2 H _5+ H _2 \rightarrow C _2 H _5+ C _2 H _6[/tex]

[Terjawab] a) You're tasked with setting up a chemistry experiment in a laboratory to synthesise a new compound. Choose five apparatuses you would use for this experiment. For each one: * Describe its primary function. * Explain how it contributes to the successful execution of the experiment. * Provide an example of a specific experiment where this apparatus would be essential. b) Discuss five essential laboratory safety protocols that must be followed to ensure safety in the laboratory. For each protocol: * Explain the safety procedure. * Discuss the potential consequences if the protocol is not followed properly. Question 2. Identify and describe three common separation techniques. Explain the principle behind how it works and provide an example of a chemical process or experiment where this technique would be used to separate components.

[Terjawab] Two masses of gold were measured before they were melted down. What is the total mass of the gold, reported to the appropriate number of significant figures? $\begin{array}{r} 15.650 g \ +10.23 g \ \hline[?] g \end{array}$

[Terjawab] Consider the following intermediate chemical equations: [tex]$\begin{array}{l} 2 H_2(g)+O_2(g) \rightarrow 2 H_2 O(l) \ H_2(g)+F_2(g) \rightarrow 2 HF(g) \end{array}$[/tex] In the final chemical equation, HF and [tex]$O _2$[/tex] are the products that are formed through the reaction between [tex]$H _2 O$[/tex] and [tex]$F _2$[/tex]. Before you can add these intermediate chemical equations, you need to alter them by multiplying the A. second equation by 2 and reversing the first equation. B. first equation by 2 and reversing it. C. first equation by (1 / 2) and reversing the second equation. D. second equation by 2 and reversing it.

[Terjawab] Consider the following intermediate chemical equations: [tex]$\begin{array}{l} 2 H_2(g)+O_2(g) \rightarrow 2 H_2 O(l) \ H_2(g)+F_2(g) \rightarrow 2 HF(g) \end{array}$[/tex] In the final chemical equation, HF and [tex]$O _2$[/tex] are the products that are formed through the reaction between [tex]$H _2 O$[/tex] and [tex]$F _2$[/tex]. Before you can add these intermediate chemical equations, you need to alter them by multiplying the A. second equation by 2 and reversing the first equation. B. first equation by 2 and reversing it. C. first equation by (1 / 2) and reversing the second equation. D. second equation by 2 and reversing it.