Answer:
<u><em>See attachment for explanations.</em></u>
Explanation:
The atomic number in an element is usually how many protons the element has. For example, Hydrogen has a 1 on top of the H (on the periodic table), therefore, Hydrogen has 1 proton. Oxygen has an 8 on top of the O (on the periodic table) so therefore, Oxygen has 8 protons.
Answer:
Molar mass→ 0.930 g / 6.45×10⁻³ mol = 144.15 g/mol
Explanation:
Let's apply the formula for freezing point depression:
ΔT = Kf . m
ΔT = 74.2°C - 73.4°C → 0.8°C
Difference between the freezing T° of pure solvent and freezing T° of solution
Kf = Cryoscopic constant → 5.5°C/m
So, if we replace in the formula
ΔT = Kf . m → ΔT / Kf = m
0.8°C / 5.5 m/°C = m → 0.0516 mol/kg
These are the moles in 1 kg of solvent so let's find out the moles in our mass of solvent which is 0.125 kg
0.0516 mol/kg . 0.125 kg = 6.45×10⁻³ moles. Now we can determine the molar mass:
Molar mass (mol/kg) → 0.930 g / 6.45×10⁻³ mol = 144.15 g/mol
To find this, we will use this formula:
Molar mass of element
------------------------------------ x 100
Molar mass of compound
So, first lets calculate the mass of the compound as a whole. We use the atomic masses on the periodic table to determine this.
Ca: 40.078 g/mol
N2 (there is two nitrogens): 28.014 g/mol
O6 (there are six nitrogens: 3 times 2): 95.994 g/mol
When we add all of those numbers up together, we get 164.086. That is the molar mass for the whole compound. However, we are trying to figure out what percent of the compound oxygen makes up. From the molar mass, we know that 95.994 of the 164.086 is oxygen. Lets plug those numbers into our equation!
95.994
-----------
164.086
When we divide those two numbers, we get .585. When we multiply that by 100, we get 58.5.
So, the percent compostition of oxygen in Ca(NO3)2, or, calcium nitrate, is 58.5%.
Answer:
The minimum rate of fresh air in the room is 176 moles/min
Explanation:
High exposure of CO₂ has health effects as headaches, increased heart rate, elevated blood pressure, coma, asphyxia, convulsions, etc.
0,500 mole% of CO₂ in air means 0,500 moles of CO₂ per 100 moles of air
As the rate of sublimation of CO₂ is 0,880, the minimum rate of fresh air in the room must be:
X = <em>176 moles of Air/min</em>
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I hope it helps!
