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Questions in chemistry

📝 Answered - Which of the following is a proper safety precaution when transporting nitrogen cylinders? A. All answers are correct B. Use an approved cart C. Secure the cylinder D. Ensure the cap is secured on the cylinder

📝 Answered - Sodium hydroxide $(NaOH)$ was added to pure water $(H_2O)$. Which most likely were the pH values of the water before and after the sodium hydroxide was added to it? A. before = 7, after = 9 B. before = 7, after = 4 C. before = 4, after = 7 D. before = 9, after = 7

📝 Answered - Which is an important safety precaution to be followed when working with refrigerants? A. Never expose refrigerant vapors to an open flame or direct heat source B. Never use a torch to raise the pressure in a refrigerant cylinder C. Ensure the area is well ventilated D. All answers are correct

📝 Answered - Which metallic component of firearm discharge residues could not be detected using: A. barium B. antimony C. lead D. carbon

📝 Answered - What is K for a reaction if ∆G° = -347.2 kJ/mol at 25.00 °C? Give your answer to four significant figures. (R = 8.314 J/mol·K)

📝 Answered - Four different thermometers were used to measure the temperature of a sample of impure boiling water. The measurements are recorded in the table below. | Thermometer | Temperature Reading 1 | Temperature Reading 2 | Temperature Reading 3 | | :---------- | :-------------------- | :-------------------- | :-------------------- | | W | $100.1^{\circ} C$ | $99.9^{\circ} C$ | $96.9^{\circ} C$ | | X | $100.4^{\circ} C$ | $102.3^{\circ} C$ | $101.4^{\circ} C$ | | Y | $90.0^{\circ} C$ | $95.2^{\circ} C$ | $98.6^{\circ} C$ | | Z | $90.8^{\circ} C$ | $90.6^{\circ} C$ | $90.7^{\circ} C$ | The actual boiling point of pure water is $100.0^{\circ} C$. What can be concluded from the data about the reliability and validity of the thermometers? A. Thermometer $Z$ is the most reliable. B. Thermometer $X$ has the highest validity. C. Thermometer $W$ is the most reliable. D. Thermometer $Y$ has the highest validity.

📝 Answered - QUESTION 1: THERMOCHEMISTRY a) An LP gas tank in a home barbeque contains 13.2 kg of propane, [tex]C _3 H _8[/tex]. Calculate the heat (in kJ ) associated with the complete combustion of all of the propane in the tank. [tex]C_3 H_8(g)+5 O_2(g) \longrightarrow 3 CO_2(g)+4 H_2 O(g) \Delta H_{run}=-2044 kJ[/tex]

📝 Answered - What is the molality of a solution that has 3 mol of glucose in 6 kg of water? A. $\frac{3 mol}{6 L}$ B. $\frac{3 kg}{6 L}$ C. $\frac{3 mol}{6 kg}$ D. $\frac{6 kg}{3 mol}$

📝 Answered - Which classification of matter includes materials that can no longer be identified by their individual properties? A) Element B) Mixture C) Compound D) Atom

📝 Answered - Identify the reactants in the reaction [tex]HCl + NaOH \rightarrow NaCl + H _2 O[/tex]. A. HCl and NaOH B. Na and Cl C. H and Cl D. NaCl and [tex]H _2 O[/tex]