Why is it important to always subtract the earlier value from the later value when finding the change in mass,instead of always
1 answer:
Mass and energy are inter convertible.As per Einsteins mass and energy relations i.e ,some amount of energy is lost that is converted into energy .
In our day to day life ,generally mass is lost and energy is formed. In a ideal assumption we subtract the mass of earlier one from the later one which indirectly denotes that some amount of mass is lost and energy is released .There is also endothermic reactions where energy is needed which does not mean mass is added.Here simply energy is needed to initiate the reactions.
So instead of subtracting the smaller value from lager we subtract the initial value from final as the latter one can explain a physical phenomenon in a better way.we can get some in formation from it.
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Answer:
c.
Explanation:
- In absence of friction, total mechanical energy must be conserved.
- This means that the change in gravitational potential energy (in magnitude) must be equal to the change in kinetic energy:
- As it can be seen, the mass m is on the both sides of the equation, which means that it can be simplified.
- We can solve this equation for v (speed at the bottom) as follows:
- As it can be seen, the mass has no part in the equation, so, due both are starting from the same height, both people have the same speed at the bottom.
- The option c is the right one.
Answer:
The volume of the final solution, V = 0.0305L
Explanation:
Number of moles = Concentration * volume
Concentration of HA = 1.00 * 10⁻⁴M
Volume of HA = 1000mL = 1 L
Number of moles of HA = 1.00 * 10⁻⁴ * 1
Number of moles of HA = 1.00 * 10⁻⁴ mols
Equation of reaction:
HA → H⁺ + A⁻
If 1 mol of HA produces 1 mol of H⁺ and A⁻, 1.00 * 10⁻⁴ mol of HA will produce 1.00 * 10⁻⁴ mol of H⁺ and A⁻.
Since only 16% dissociation occurs = 0.16
Number of moles of H⁺ produced = 0.16 * 1.00 * 10⁻⁴
Number of moles of H⁺ produced = 1.6 * 10⁻⁵mols
Number of moles of A⁻ produced = 0.16 * 1.00 * 10⁻⁴
Number of moles of A⁻ produced = 1.6 * 10⁻⁵mols
Since 16% of HA dissociated into H⁺ and A⁻, 84% of HA is left
Number of mols of HA left = 0.84 * 1.00 * 10⁻⁴
Number of mols of HA left = 8.4 * 10⁻⁵mols
Concentration = num of moles/volume
Let the volume of the final solution be V
Conc of HA = 8.4 * 10⁻⁵/V
Conc of H⁺ = 1.6 * 10⁻⁵/V
Conc of A⁻ = 1.6 * 10⁻⁵/V
To calculate the dissociation constant