Answer:
Explanation:
The<em> energy of a photon</em>, E, can be calculated with the Planck-Einstein equation:
Where:
- h is Planck's constant 6.626×10⁻³⁴ J.s, and
- f is the frequency of the photon or electromagnetic radiation.
Substituting with your data:
Now multiply by Avogadro's number to obtain the energy of one mole of photons:
Answer:
4 g after 58.2 years
0.0156 After 291 years
Explanation:
Given data:
Half-life of strontium-90 = 29.1 years
Initially present: 16g
mass present after 58.2 years =?
Mass present after 291 years =?
Solution:
Formula:
how much mass remains =1/ 2n (original mass) ……… (1)
Where “n” is the number of half lives
to find n
For 58.2 years
n = 58.2 years /29.1 years
n= 2
or 291 years
n = 291 years /29.1 years
n= 10
Put values in equation (1)
Mass after 58.2 years
mass remains =1/ 22 (16g)
mass remains =1/ 4 (16g)
mass remains = 4g
Mass after 58.2 years
mass remains =1/ 210 (16g)
mass remains =1/ 1024 (16g)
mass remains = 0.0156g
Answer
5
Explanation:
We can go about this using the percentage compositions.
First, we calculate the percentage composition of the copper sulphate. This is obtainable by using the mass.
0.96/1.5 * 100 = 64%
Hence the percentage by mass of the water present is 36%
The molar mass of the anhydrous sulphate is 64 + 32 +4(16) = 160g/mol
The molar mass of the water is 2(1) + 16 = 18g/mol
Not forgetting that it is in multiples of x, the total molar mass of the water is 18x moles
The total mass of the copper sulphate hydrate is 160+ 18x
Now how do we get x? Like it is said earlier, the percentage composition is constant.
Hence, 64/100 * (160 + 18x) = 160
16000 = 64(160 + 18x)
16000 = 10,240 + 1152x
16,000 - 10,240 = 1152x
1152x = 5760
x = 5760/1152
x = 5
Answer:
8.9 KJ
Explanation:
Given data:
Mass of strip = 251 g
Initial temperature = 22.8 °C
Final temperature = 75.9 °C
Specific heat capacity of granite = 0.67 j/g.°C
Solution:
Specific heat capacity:
It is the amount of heat required to raise the temperature of one gram of substance by one degree.
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
ΔT = 75.9 °C - 22.8 °C
ΔT = 53.1 °C
Q = 251 g × 0.67 j/g.°C × 53.1 °C
Q = 8929.8 J
Jolue to KJ.
8929.8J ×1 KJ / 1000 J
8.9 KJ
First, multiply the mass by the molar mass of neon to find out how many moles of neon there are. Then, multiply by 22.4 to find out how many liters there are.
6.745g Ne x 1 mole Ne/20 g Ne x 22.4 L/1 mole Ne = 7.5544 L
