Dmitri Mendeleev, he realized that the physical and chemical properties of elements were related to their atomic mass and arranged them into groups (columns)
Answer:
23.34 %.
Explanation:
- The percentage of water must be calculated as a mass percent.
- We need to find the mass of water, and the total mass in one mole of the compound. For that we need to use the atomic masses of each element and take in consideration the number of atoms of each element in the formula unit.
- <em>Atomic masses of the elements:</em>
Cd: 112.411 g/mol, N: 14.0067 g/mol, O: 15.999 g/mol, and H: 1.008 g/mol.
- <em>Mass of the formula unit:</em>
Cd(NO₃)₂•4H₂O
mass of the formula unit = (At. mass of Cd) + 2(At. mass of N) + 10(At. mass of O) + 8(At. mass of H) = (112.411 g/mol) + 2(14.0067 g/mol) + 10(15.999 g/mol) + 8(1.008 g/mol) = 308.5 g/mol.
- <em> Mass of water in the formula unit:</em>
<em>mass of water</em> = (4 × 2 × 1.008 g/mol) + (4 × 15.999 g/mol) = 72.0 g/mol.
- <em>So, the percent of water in the compound = [mass of water / mass of the formula unit] × 100 = [(72.0 g/mol)/(308.5 g/mol)] × 100 = 23.34 %</em>
An exothermic reaction is a type of chemical reaction in which energy is released to the environment in form of heat or light. Endothermic reaction in the other hand is a chemical reaction where energy is taken from the surroundings and thus the surroundings end up with less energy than they started with. In this case; the above reaction is an Exothermic reaction (heat is being released to the surroundings).
<span>The rate of infusion is 2.1L/19h or 2100mL/19h (as 1L = 100 mL).
To convert 19 hours to minutes we multiply as follows:
19 hours = (19 hours) x (60 minutes/1 hour) = 1140 minutes
So the rate of infusion becomes:
2100mL /1140 min
In order to converted mL to drops (gtt) we multiply the rate of infusion with the drop factor to get the drip rate:
(2100mL/1140min) x (20 gtt/mL) = 36.8 gtt/min</span>
Answer:
10425 J are required
Explanation:
assuming that the water is entirely at liquid state at the beginning , the amount required is
Q= m*c*(T final - T initial)
where
m= mass of water = 25 g
T final = final temperature of water = 100°C
T initial= initial temperature of water = 0°C
c= specific heat capacities of water = 1 cal /g°C= 4.186 J/g°C ( we assume that is constant during the entire temperature range)
Q= heat required
therefore
Q= m*c*(T final - T initial)= 25 g * 4.186 J/g°C * (100°C- 0°C) = 10425 J
thus 10425 J are required
