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4 water cannot exist as a liquid at 5 c correct 5

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4. Water cannot exist as a liquid at - 5 C. correct 5. Water cannot exist as a liquid at pressures below 4.6 torr. Explanation: Starting in the solid phase of water and in- creasing the pressure ( i.e. , increasing density) it becomes liquid and vice versa. The liq- uid section for carbon dioxide is to the right of - 57 . By increasing pressure water can remain liquid at temperatures well below its standard freezing point. The liquid section for water is completely above 4.6 torr. Any point for carbon dioxide that is below - 78 and above 1 atm is in the solid section. 006 3.3points Write the equation for the dissolution of NH 4 NO 3 in water. If 3.18 mol of NH 4 NO 3 are dissolved, how many total moles of ions are produced?

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casey (rmc2555) – Homework 2 – holcombe – (51395) 3 Correct answer: 6 . 36 mol. Explanation: n solute = 3 . 18 mol NH 4 NO 3 solvent is H 2 O n total = ? NH 4 NO 3 (s) H 2 O ----→ NH + 4 (aq) + NO 3 (aq) Therefore 3 . 18 mol NH + 4 +3 . 18 mol NO 3 = 6 . 36 mol ions were produced. 007 3.3points Which of the following sets of values for ΔH lattice , ΔH hydration and ΔH solution , respec- tively, could describe a salt that dissolves en- dothermicly? 1. 69, - 52 and 17 kJ · mol 1 correct 2. - 35, 97 and - 33 kJ · mol 1 3. 69, 45 and 24 kJ · mol 1 4. - 35, - 86 and - 33 kJ · mol 1 Explanation: ΔH lattice + ΔH hydration = ΔH solution Keeping in mind that ΔH lattice is always en- dothermic, ΔH hydration is always exothermic, and ΔH solution is the sum of the two and for this problem must be endothermic, only the values 69, - 52 and 17 kJ · mol 1 satisfy these constraints. 008 3.3points Which of the following liquids has the LOW- EST viscosity? 1. benzene correct 2. phosphoric acid 3. ethanol 4. water Explanation: In general, the stronger the intermolecular forces, the higher the viscosity of the sub- stance. All of the species except benzene are polar and will have dipole-dipole interactions; additionally, water and ethanol are capable of hydrogen bonding. All species exhibit disper- sion forces. Benzene is a non-polar molecule that is not too much larger than the other species, so it will have relatively weak disper- sion forces and thus the lowest viscosity. 009 3.3points Which of the following would increase the solubility of nitrogen gas, N 2 (g), in the solvent water? I) changing to a less polar solvent II) increasing the amount of solvent III) increasing the pressure of N 2 (g) 1. I and II 2. I, II and III 3. I only 4. II only 5. II and III 6. III only 7. I and III correct Explanation: The solubility of a gas is directly propor- tional to the gas’ pressure, inversely propor- tional to the temperature of the solvent. Con- sidering the principle of like dissolve like, a non-polar species such as N 2 (g) will be more soluble in non-polar solvents. The volume of the solvent does not impact the solubility, which is an intensive property; this is evident when one considers the unity of solubility such as grams per liter, etc.
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