Q6. 3
Q7. 3
Q8. pH
Q18. 3
Q19. 3
Q20. 4
Hope this helped??
Answer and explanation:
A chemical change occurs when new substances or materials are produced to have different chemical properties from the reactants.
Some examples of this are paper burning, fruit rotting, and metal rusting.
Answer:
D) Potential Energy
Explanation:
The compressed spring has elastic potential energy. If it is allowed to de-compress, the elastic potential energy will be converted to kinetic energy.
You have 0.50 mol of NH3 and 0.20 mol of NH4+ to start (NH4Cl dissolves completely), given the molarity and 1.0 L solution.
30.0 mL of 1.0 M HCl is 0.0300 mol of HCl. This will react with the NH3 to produced 0.030 mol of NH4+.
You now have 0.47 mol NH3 and 0.23 mol NH4+. Now use the Henderson-Hasselbach equation to calculate your pH. The equation says to use concentration of acid and base, but you can just use the moles of them because it doesn’t make a difference.
pH = pKa + log(base/acid)
pKa = 14 - pKb = 14 - 4.75 = 9.25
pH = 9.25 + log(0.47/0.23) = 9.56