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Questions in chemistry

📝 Answered - The table shows the percentages of hydrocarbons that are found in a sample of crude oil. | Hydrocarbons | Percentage | |---|---| | paraffins | 30 | | naphthenes | 49 | | aromatics | 15 | | asphaltics | 6.0 | Based on the given information, what is the best classification for this sample of crude oil? A. an element B. a pure compound C. a pure substance D. a mixture

📝 Answered - Carbon reacts with oxygen to produce carbon dioxide ($CO_2(g), \Delta H_{f }=-393.5 kJ / mol$) according to the equation below. $C(s)+2 O_2(g) \rightarrow CO_2(g)$ What is the enthalpy change of the reaction? Use $\Delta H_{r \times n}=\sum\left(\Delta H_{t, \text { products }}\right)-\sum\left(\Delta H_{t, \text { reactants }}\right)$. A. -393.5 kJ B. -196.8 kJ C. 196.8 kJ D. 393.5 kJ

📝 Answered - If you need to multiply the following reaction by 2 to be an intermediate reaction in a Hess's law problem, what would be the final value for the enthalpy of reaction you use for this intermediate reaction? $H_2+0.5 O_2 \rightarrow H_2 O, \Delta H=-286 kJ$ A. 286 kJ B. -572 kJ C. -286 kJ D. 572 kJ

📝 Answered - Item | Future State Container | Why? (Short) ---|---|--- Carade | Solid Liquid | Milch | Solid Liquid | LIG | Liquid Gas | Spoon | Solid | Juice | Solid Liquid | Solids: definite shape and volume Liquids: no definite shape, but definite volume Gases: no definite shape or volume

📝 Answered - Why is the second electron affinity of an atom usually shown by a positive sign?

📝 Answered - 1.6 Which ONE of the following is a CORRECT description for a 0.1 mol·dm⁻³ hydrochloric acid solution? A) Dilute strong acid B) Dilute weak acid C) Concentrated weak acid D) Concentrated strong acid 1.7 Consider the reactant Y in the following reaction: Y + H₂O ⇌ H₃O⁺ + H₂PO₄⁻ A) PO₄³⁻ B) H₂PO₄⁻ C) HPO₄²⁻ D) H₃PO₄ 1.8 An aqueous solution that contains more hydronium ions than hydroxide ions is a(n) A) basic solution B) acidic solution C) neutral solution D) standardised solution 1.9 Consider the reaction represented by the equation below: H₃PO₄(aq) + HCO₃⁻(aq) ⇌ H₂PO₄⁻(aq) + H₂CO₃(aq) Kₐ > 1 The strongest base in the above reaction is: A) H₂PO₄⁻ B) HCO₃⁻ C) H₃PO₄ D) H₂CO₃

📝 Answered - Calculate the specific heat of reaction of C3H8(l) at standard state for the following reaction using the data given in the table below: C3H8(l) + O2(g) → CO2(g) + 4H2O(l) | Compound | -ΔHf° [kcal/gmol] | ΔHvaporization at 25°C [kcal/gmol] | |---|---|---| | C3H8(l) | - | 3.823 | | C3H8(g) | 24.806 | - | | CO2(l) | - | 1.263 | | CO2(g) | 93.995 | - | | H2O(l) | - | 10.499 | | H2O(g) | 57.763 | - |

📝 Answered - 9. The solubility of ______ decreases as the temperature is raised. (A) CaO (B) CaCO₃ (C) Ca(OH)₂ (D) NaCl 10. How does stirring affect the solubility of a solid? (A) Increase the pressure (B) Increase the temperature (C) Increases the rate of dissolution of the solute in the solvent (D) Increase the reactivity of the solute and solvent

📝 Answered - $H _2 SO _4( aq )$ and $KOH ( aq )$ $\\\xrightarrow[\\text { Molecular Equation }]{H_2 SO_4(aq)+KOH(aq) \\rightarrow}$ Complete Ionic Equation Net Ionic Equation Spectator Ions

📝 Answered - Which refers to the amount of a solute that will dissolve in a given volume of solvent at a given temperature and pressure? A. solubility B. supersaturated C. dissolution rate D. concentrated