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Questions in chemistry

📝 Answered - Which of the following is NOT a sign of a CO2 leak? A. Frost on the tank B. A strong chemical odor C. Hissing or whistling noises

📝 Answered - Select the correct answer. What is the theoretical yield of methanol [tex]$\left( CH _3 OH \right)$[/tex] when 12.0 grams of [tex]$H _2$[/tex] is mixed with 74.5 grams of CO? [tex]$CO +2 H _2 \rightarrow CH _3 OH$[/tex] A. 14.88 grams B. 47.65 grams C. 74.50 grams D. 85.12 grams E. 92.04 grams

📝 Answered - Daseous nyarogen burns in the presence of oxygen to form water: [tex]2 H_2+O_2 \rightarrow 2 H_2 O+ \text { energy }[/tex] Which molecule is oxidized and what kind of bond is formed? A. Oxygen, polar. B. Hydrogen, polar. C. Oxygen, nonpolar. D. Hydrogen, nonpolar.

📝 Answered - A typical aspirin tablet contains 323 mg acetylsalicylic acid [tex]$\left( HC _9 H _7 O _4\right)$[/tex]. Calculate the pH of a solution that is prepared by dissolving two aspirin tablets in enough water to make one cup (237 mL) of solution. Assume the aspirin tablets are pure acetylsalicylic acid, [tex]$K_{ a }=3.3 \times 10^{-4}$[/tex].

📝 Answered - The concentration of hydronium ions $(H_3 O ^{\prime})$ in a solution of (a) Calculate the concentration of hydroxide ions (OHF) in the solution of hydrofluoric acid (HF) at $25^{\circ} C$. (b) Write down the expression for the equilibrium constant for reaction (i). Calculate the concentration of un-ionised hydrofluoric in the solution at $25^{\circ} C$. for the hydrolysis of $NH _4 NO _3$ in water as represented by chemical equations below:

📝 Answered - Consider the chemical equations shown here. [tex]\begin{array}{l} P_4(s)+3 O_2(g) \rightarrow P_4 O_6(s) \quad \Delta H_1=-1,640.1 kJ \ P_4 O_{10}(s) \rightarrow P_4(s)+5 O_2(g) \quad \Delta H_2=2,940.1 kJ\\ \end{array}[/tex] What is the overall enthalpy of reaction for the equation shown below? Round the answer to the nearest whole number. [tex]P_4 O_6(s)+2 O_2(g) \rightarrow P_4 O_{10}(s)[/tex]

📝 Answered - 4. a) State the scientific principle involved in each of the following local industries: i. kenkey production ii. soap production iii. salt production iv. vegetable crop production v. gari processing (5marks) b) i. What is an alloy? ii. Name the main elements present in each of the following alloys: (a) Nichrome (B) Duralumin (y) Bronze (5marks).

📝 Answered - What is the pH of a [tex]$3.60 \times 10^{-6} M$[/tex] solution of the strong acid [tex]$HClO_4$[/tex]? [tex]$\begin{array}{l} HClO_4(aq)+H_2 O(\ell) \rightarrow ClO_4^{-}(aq)+H_3 O^{+}(aq) \ {\left[HClO_4\right]_0=3.60 \times 10^{-6}} \end{array}$[/tex]

📝 Answered - Compare and contrast physical and chemical changes in terms of molecular structure.

📝 Answered - Choose the complex which is paramagnetic: (i) [Fe(H2O)6]2+ (ii) K3[Cr(CN)6] (iii) K3[Fe(CN)6] (iv) K2[Ni(CN)4]