Answer:
160.3g
Explanation:
We know the equation:
No of moles = mass ÷ Mass of element
We need to find the mass, so make mass the subject of the formula.
Mass = No. of moles × mass of element
Mass = 5 × 32.06
Mass = 160.3g
Answer:
If the pKa of the acid is low (negative), then the acid is strong.
Explanation:
Ka, <em>the acid ionization constant, </em>measures the strength of an acid in a solution. Stronger acids have higher Ka values.
We defined: pKa = -log[Ka]
This function is a decreasing function, meaning that pKa will be getting smaller and smaller, while increasing Ka (high values of Ka will have negative pKa values). Therefore, stronger acids (high values of Ka), will have low (negative) pKa values.
Answer:
The forward reaction is exothermic.
Explanation:
- Le Châtelier's principle states that when there is an dynamic equilibrium, and this equilibrium is disturbed by an external factor, the equilibrium will be shifted in the direction that can cancel the effect of the external factor to reattain the equilibrium.
- When the mixture turned darker brown, this means that the reaction is shifted towards the left direction (reactants side).
- The temperature is increased and the reaction shifted to the reverse direction, this means that the forward direction is exothermic.
- Exothermic reaction releases heat and when increasing the temperature, the reaction will be shifted to the reverse direction to suppress the effect of increasing the temperature.
- <em>So the right choice is: The forward reaction is exothermic. </em>
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I don't know this article, but I do know some major changes: first, the change from the plum pudding model (no nucleus, just electrons) to the gold foil experiment, which had Rutherford shoot alpha particles at a sheet of gold only to find them rebounding, proving the existence of a positively charged mass, i.e a nucleus, in the atom. However, this changed again when Bohr realized that the negatively charged electrons should be attracted to the positively charged center, so that there must be something else inside the nucleus.