Three bottles are labelled as shown:
Bottle 1 0.001 mol/L HCl(aq)
Bottle 2 0.003 mol/L HBr(aq)
Bottle 3 0.002 mol/L KOH(aq)
Arrange the bottles in order of decreasing pH.
a) Bottle 3 > Bottle 1 > Bottle 2
b) Bottle 2 > Bottle 1 > Bottle 3
c) Bottle 1 > Bottle 2 > Bottle 3
d) Bottle 3 > Bottle 2 > Bottle 1
e) Bottle 2 > Bottle 3 > Bottle 1
To determine the order of decreasing pH, we need to consider the acidic or basic nature of the solutions. HCl is a strong acid, and HBr is also a strong acid. KOH is a strong base.
Since the pH is a measure of the concentration of H+ ions in a solution, a higher concentration of H+ ions corresponds to a lower pH.
Thus, the order of decreasing pH is:
b) Bottle 2 > Bottle 1 > Bottle 3
are you sure?
Apologies for the confusion. I made an error in my previous response.
To determine the order of decreasing pH, we need to consider the concentration of H+ ions in the solutions. The higher the concentration of H+ ions, the lower the pH.
HCl is a strong acid, meaning it dissociates completely in water to produce H+ ions. Therefore, the concentration of H+ ions in Bottle 1 is 0.001 mol/L, making it the highest concentration of H+ ions among the three bottles.
HBr is also a strong acid, so the concentration of H+ ions in Bottle 2 is 0.003 mol/L. This is higher than the concentration in Bottle 3.
KOH is a strong base and produces OH- ions when dissolved in water. Therefore, Bottle 3 is basic, and the concentration of H+ ions is low compared to Bottles 1 and 2.
Based on this information, the correct order of decreasing pH is:
c) Bottle 1 > Bottle 2 > Bottle 3
What is the correct answer?
I apologize for the confusion. The correct answer is:
d) Bottle 3 > Bottle 2 > Bottle 1
To determine the order of decreasing pH, we need to understand the concept of pH and the properties of the given solutions.
pH is a measure of the acidity or alkalinity of a solution and is determined based on the concentration of hydrogen ions (H+) present in the solution. The pH scale ranges from 0 to 14, where a lower pH value indicates higher acidity and a higher pH value indicates higher alkalinity.
In this case, we have three solutions: HCl(aq), HBr(aq), and KOH(aq).
HCl and HBr are both strong acids, meaning they fully dissociate in water and release hydrogen ions. KOH is a strong base that also fully dissociates in water and releases hydroxide ions (OH-).
Comparing the three solutions:
1. HCl(aq): The formula for hydrochloric acid is HCl. It dissociates fully into H+ and Cl- ions. Since the concentration is 0.001 mol/L, we have 0.001 mol/L of H+ in solution.
2. HBr(aq): The formula for hydrobromic acid is HBr. It dissociates fully into H+ and Br- ions. Since the concentration is 0.003 mol/L, we have 0.003 mol/L of H+ in solution.
3. KOH(aq): The formula for potassium hydroxide is KOH. It dissociates fully into K+ and OH- ions. Since the concentration is 0.002 mol/L, we have 0.002 mol/L of OH- in solution. To calculate the H+ concentration, we can use the fact that water dissociates to give equal amounts of H+ and OH- ions. This means that the concentration of H+ ions in the solution would be equal to the concentration of OH- ions, which is 0.002 mol/L.
Comparing the concentrations of H+ ions, we find:
HCl(aq) < HBr(aq) < KOH(aq)
Since a higher concentration of H+ ions indicates lower pH (greater acidity), the order of decreasing pH is:
Bottle 2 > Bottle 3 > Bottle 1
Therefore, the correct answer is e) Bottle 2 > Bottle 3 > Bottle 1.