Final answer:
Lemon juice with a pH of 2 has a significantly higher concentration of hydronium ions than soap, which usually has a pH around 9-10. The difference is a factor of at least 10^9 to 10^10, making lemon juice far more acidic.
Step-by-step explanation:
The answer to the question of which has the greater concentration of hydronium ions, soap or lemon juice, depends on their respective pH levels. Lemon juice has a pH of about 2, which means it has a high concentration of hydronium ions.
Soap typically has a pH level that is much higher, usually around 9-10, indicating a lower concentration of hydronium ions and a higher concentration of hydroxide ions. Given that each pH unit represents a tenfold difference in ion concentration, lemon juice has a significantly higher concentration of hydronium ions compared to soap.
Lemon juice with a pH of 2 has a 107 times higher concentration of hydronium ions compared to pure water (pH 7). In contrast, soap with a pH of around 9-10, compared to pure water, would have a lower concentration of hydronium ions by a factor of 102 to 103 times.
Therefore, lemon juice is far more acidic and has a higher concentration of hydronium ions than soap by a factor of at least 109 to 1010 times. This acidic property of lemon juice makes it more capable of performing tasks such as dissolving stains or adding tartness to food.