Answer: 5.5
Explanation: Strontium titanate is both much denser (specific gravity 4.88 for natural, 5.13 for synthetic) and much softer (Mohs hardness 5.5 for synthetic, 6–6.5 for natural) than diamond.
Answer:
No, it is not sufficient
Please find the workings below
Explanation:
Using E = hf
Where;
E = energy of a photon (J)
h = Planck's constant (6.626 × 10^-34 J/s)
f = frequency
However, λ = v/f
f = v/λ
Where; λ = wavelength of light = 325nm = 325 × 10^-9m
v = speed of light (3 × 10^8 m/s)
Hence, E = hv/λ
E = 6.626 × 10^-34 × 3 × 10^8 ÷ 325 × 10^-9
E = 19.878 × 10^-26 ÷ 325 × 10^-9
E = 19.878/325 × 10^ (-26+9)
E = 0.061 × 10^-17
E = 6.1 × 10^-19J
Next, we work out the energy required to dissociate 1 mole of N=N. Since the bond energy is 418 kJ/mol.
E = 418 × 10³ ÷ 6.022 × 10^23
E = 69.412 × 10^(3-23)
E = 69.412 × 10^-20
E = 6.9412 × 10^-19J
6.9412 × 10^-19J is required to break one mole of N=N bond.
Based on the workings above, the photon, which has an energy of 6.1 × 10^-19J is not sufficient to break a N=N bond that has an energy of 6.9412 × 10^-19J
Answer:
The answer is option 3, C5H12 + 8O2 → 5CO2 + 6H2O.
Explanation:
In an exothermic reaction, the energy change(ΔH) will always be a negative value.
For endothermic reaction, the energy change's value is positive.
In the options above, option 1 and 2 are endothermic reaction.
Answer:
2 Fe(iii)2O3 + 3 C ==> 2 Fe + 3 CO2
Explanation:
First of all, you have to translate the words into an equation.
Fe(iii)2O3 + C ==> Fe + CO2
The easiest way to tackle this is to start with the Oxygens and balance them. They must balance by going to the greatest common factor which is 6. So you multiply the molecule by whatever it takes to get the Oxygens to 6
2 Fe(iii)2O3 + C ==> Fe + 3 CO2
Now work on the irons. There 2 on the left and just 1 on the right. So you need to multiply the iron by 2.
2 Fe(iii)2O3 + C ==> 2 Fe + 3 CO2
Finally it is the turn of the carbons. There are 3 on the right, so you must make the carbon on the left = 3
2 Fe(iii)2O3 + 3 C ==> 2 Fe + 3 CO2
And you are done.
