Answer:
T2 = 29°C
Explanation:
Given data:
Heat added = 420 j
Mass of water = 25 g
Initial temperature = 25°C
Final temperature = ?
Solution;
Specific heat capacity:
It is the amount of heat required to raise the temperature of one gram of substance by one degree.
Specific heat capacity of water = 4.18 j/g.°C
Formula:
Q = m.c. ΔT
Q = amount of heat absorbed or released
m = mass of given substance
c = specific heat capacity of substance
ΔT = change in temperature
Now we will put the values.
420 j = 25 g ×4.18 j/g.°C × (Final temperature - initial temperature)
420 j = 25 g ×4.18 j/g.°C × (T2 - 25°C)
420 j = 104.5 j/°C × (T2 - 25°C)
420 j /104.5 j/°C = T2 - 25°C
4°C + 25°C = T2
T2 = 29°C
For waves:
speed = frequency x wavelength
speed = 3 x 10⁸
frequency = 9192631770 Hz
wavelength = 3 x 10⁸ / (9192631770)
wavelength = 0.033 meters
This wavelength lies in the region of microwaves.
Answer: a. 0.75m (NH4)3PO4 will have the lowest freezing point .
Explanation: Freezing point decreases as the concentration of the solute substance increases. Assuming the same solvent for all of them, for instance water.
∆T= i.Kf.b
∆T= freezing point depression
i= vant Hoff factor
Kf= molality
Assuming water to be the solvent for all Kf=1.86°C/M
VANT HOFF FACTORS :
For (NH4)3PO4
This has 3 ionic bonding and 1 covalent bonding making it 4 bond
Therefore i=4
For CaSO4
This has 1 metallic bond and 1 covalent bond making it 2 bond.
Therefore i=2
For LiCl
This has 1 metallic bond and 1 non metallic bond making it 2 bond.
Therefore i=2
For CH3OH
This has only 1 covalent bond.
Therefore i=1
MOLALITY:
(NH4)3PO4 = 0.75M
CaSO4= 1.0M
LiCl= 1.0M
CH3OH= 1.5M
FREEZING POINT DEPRESSION:
For (NH4)3PO4
∆T= 4×0.75×1.86=5.58°C
For CaSO4
∆T= 2×1.0×1.86=3.72°C
For LiCl
∆T = 2×1.0×1.86= 3.72°C
For CH3OH
∆T= 1×1.5×1.86=2.79°C
REMEMBER THE HIGHER THE FREEZING POINT DEPRESSION THE LOWER THE FREEZING POINT.
FREEZING POINT DEPRESSION IS THE CHANGE IN THE FREEZING POINT PROPORTIONAL TO THE AMOUNT OF SOLUTE ADDED THE THE SOLUTION.
THEREFORE THE ONE WITH THE LOWEST FREEZING POINT IS (NH4)3PO4
Answer:
The symbol of each element is, Ne, Na, Mg, and Al.
Explanation:
Below is the list of elements that has an atomic mass of less than 19.3 u.
The atomic mass of Neon is 20.1797 u and the atomic number is 10.
The atomic mass of Sodium is 22.989769 u and the atomic number is 11.
The atomic mass of Magnesium is 24.305 u and the atomic number is 12.
The atomic mass of Aluminium is 26.981539 u and the atomic number is 13.
Here, the symbol of each element is, Ne, Na, Mg, and Al.
