Answer:
-138.9 kJ/mol
Explanation:
Step 1: Convert 235.8°C to the Kelvin scale
We will use the following expression.
K = °C + 273.15 = 235.8°C + 273.15 = 509.0 K
Step 2: Calculate the standard enthalpy of reaction (ΔH°)
We will use the following expression.
ΔG° = ΔH° - T.ΔS°
ΔH° = ΔG° / T.ΔS°
ΔH° = (-936.92kJ/mol) / 509.0K × 0.51379 kJ/mol.K
ΔH° = -3.583 kJ (for 1 mole of balanced reaction)
Step 3: Convert -9.9°C to the Kelvin scale
K = °C + 273.15 = -9.9°C + 273.15 = 263.3 K
Step 4: Calculate ΔG° at 263.3 K
ΔG° = ΔH° - T.ΔS°
ΔG° = -3.583 kJ/mol - 263.3 K × 0.51379 kJ/mol.K
ΔG° = -138.9 kJ/mol
Answer:
Freezing T° of solution = - 8.98°C
Explanation:
We apply Freezing point depression to solve this problem, the colligative property that has this formula:
Freezing T° of pure solvent - Freezing T° of solution = Kf . m
Kf = 1.86°C/m, this is a constant which is unique for each solvent. In this case, we are using water
m = molality (moles of solute / 1kg of solvent)
We convert the mass of solvent from g to kg
1.5 g . 1kg/1000g = 0.0015 kg
We convert the mass of solute, to moles. Firstly we make this conversion, from mg to g → 450mg . 1g/1000mg = 0.450 g
0.450 g. 1mol / 62.07g = 7.25×10⁻³ moles
Molality → 7.25×10⁻³ mol / 0.0015 kg = 4.83 m
- Freezing T° of solution = 1.86°C /m . 4.83 m - Freezing T° of pure solvent
-Freezing T° of solution = 1.86°C /m . 4.83 m - 0°C
Freezing T° of solution = - 8.98°C
D. Ratio of Neutrons to Protons
Answer:
Why? Because of electron shells. Technically, they're not fully inert. They have very low reactivity potential, and can only be forced to become reactive with difficulty.
Explanation:
All chemical reactivity is made possible through the atom's electron arrangement. Electrons basically have shelves where they live, called "levels" or "shells". Each level is farther from the nucleus than the previous one. Atoms are most stable when their outer most shell (called the valence shell) is full. Atoms with an incomplete shell will react with other atoms, in an attempt to either fill out the outer shell, or to rid itself of it's valence electrons so that that previous level becomes a full valence level. If the valence shell ils already full, the atom will not be inclined to create compounds.
The first shell can hold up to two electrons. After the first two electrons, any additional electrons have to begin a new shell. The second shell can hold eight electrons before it becomes full. Helium is the first noble gas on the periodic table, having two protons and two electrons. Because helium's outer most shell is full, it does not react with other atoms.
By comparison, look at hydrogen and oxygen. Oxygen has eight electrons. The first two electrons occupy the first shell. The remaining six go to the second shell. This leaves the second shell with two empty spaces that can potentially be filled. Meanwhile, hydrogen has one electron, with it's valence shell having an empty space for one additional electron. Two hydrogen atoms give up their single electrons to an oxygen atom, so that all three end up with stable valence levels.
By the time an atom can fill out the second electron shell on it's own (10 total electrons) you end up with neon, the second noble gas.
Answer:
119 protons and 179 neutrons
Explanation:
Given an element of the form AB-298, we know that 298 is the mass, which means it's the sum of the number of protons and number of neutrons.
Look at the answer choices and find the one whose numbers add up to 298. Only C (119 protons and 179 neutrons) is correct because 119 + 179 = 298.
Hope this helps!
