In 1770 a Scottish physician and Chemist Daniel Rutherford performed a simple experiment with which he discovered nitrogen. Rutherford being with an empty bottle that he turned upside down in a pan of water so that the air was trapped. A buring candle was placed inside the bottle with the trapped air causing the water to rise a bit. The part of the air that seemed to "disappear" when the candle was bured was oxygen gas and the part of the air that did not "disappear" Ruthford discovered Nitrogen.
Answer:
b. some sodium iodide will precipitate out of solution
Explanation:
We know that for salts solubility decreases as the temperature of the solution decreases. So, NaI being a salt, its solubility will surely decrease when the temperature is cooled down to 25°C from 50°C.
Thus,the undissolved sodium iodide will precipitate out of the solution.
Answer: difference in Vander Waals forces
Explanation:
The intermolecular force of attraction between the molecules in chlorine is WEAKER than that of Bromine.
This force is known as VANDER WAALS forces. And it DECREASES down the group; so Chlorine which is placed higher is a GAS, while Bromine placed lower in Group 7 is a LIQUID.
Answer:
1. 77.5g,
2. 1.78 mol,
3. 281 g
4. add 80 mL of water
Explanation:
1. Molar mass (Na2O) = 2*23.0 + 16.0 = 62.0 g/mol
1.25 mol *62.0 g/1mol = 77.5 g Na2O
2. Molar mass (KOH) = 39.1 +16.0+1.0 = 56.1 g/mol
100 g * 1 mol/56.1 g = 1.78 mol KOH
3. Molar mass (KOH) = 39.1 +16.0+1.0 = 56.1 g/mol
5 mol * 56.1g/1 mol = 281 g KOH
4. M1V1 =M2V2
M - molarity, V- volume of solution
2.0M*20mL = 0.4M*V2
V2 = 2.0*20/0.4 = 100 mL
Volume of diluted solution = 100 mL
We have 20 mL of solution, we need 100 mL of solution,
so we need to add (100-20) =80mL of water.
Take 20 ml 2.0 Molar of solution of HCl , add 80 mL of water, then we get 100 mL 0.4 M solution of HCl.
