Gravitational force -an attractive force that exists between all objects with mass; an object with mass attracts another object with mass; the magnitude of the force is directly proportional to the masses of the two objects and inversely proportional to the square of the distance between the two objects.
Answer:
A i. Internal energy ΔU = -4.3 J ii. Internal energy ΔU = -6.0 J B. The second system is lower in energy.
Explanation:
A. We know that the internal energy,ΔU = q + w where q = quantity of heat and w = work done on system.
1. In the above q = -7.9 J (the negative indicating heat loss by the system). w = 3.6 J (It is positive because work is done on the system). So, the internal energy for this system is ΔU₁ = q + w = -7.9J + 3.6J = -4.3 J
ii. From the question q = +1.5 J (the positive indicating heat into the system). w = -7.5 J (It is negative because work is done by the system). So, the internal energy for this system is ΔU₂ = q + w = +1.5J + (-7.5J) = +1.5J - 7.5J = - 6.0J
B. We know that ΔU = U₂ - U₁ where U₁ and U₂ are the initial and final internal energies of the system. Since for the systems above, the initial internal energies U₁ are the same, then we say U₁ = U. Let U₁ and U₂ now represent the final energies of both systems in A i and A ii above. So, we write ΔU₁ = U₁ - U and ΔU₂ = U₂ - U where ΔU₁ and ΔU₂ are the internal energy changes in A i and A ii respectively. Now from ΔU₁ = U₁ - U, U₁ = ΔU₁ + U and U₂ = ΔU₂ + U. Subtracting both equations U₁ - U₂ = ΔU₁ - ΔU₂
= -4.3J -(-6.0 J)= 1.7 J. Since U₁ - U₂ > 0 , U₂ < U₁ , so the second system's internal energy increase less and is lower in energy and is more stable.
Answer:
Butanoic acid present in solution
Explanation:
In this case, we have a buffer solution of butanoic acid and sodium butanoate. In other words a reaction like this:
HC₄H₇O₂ + H₂O <------> C₄H₇O₂⁻ + H₃O⁺ Ka = 1.5x10⁻⁵
The low value of Ka means that this is a weak acid. So, after this, the NaOH is added to the solution.
The NaOH is a really strong base, so we might expect that the pH of the solution increase drastically, however this do not occur.
The reason for this is because the first thing to happen in this reaction is an acid base reaction.
The NaOH react with the butanoic acid still present in solution, because is a weak acid, so in solution, this acid is not completely dissociated into it's respective ions. So the butanoic acid reacts with the NaOH and the products:
HC₄H₇O₂ + NaOH <------> Na⁺C₄H₇O₂⁻ + H₂O
So, because of this, the pH increase but not much.
