Question

As part of a lab exam, you are given a vial of orange crystals. When you add them to pure, neutral pH water, the pH changes to 13. Other tests show that the crystals consist of a single chemical. You could conclude the chemical is _______.

Answer 1

The orange crystals that increased the pH of pure water to 13 are indicative of a strong base, such as sodium hydroxide or potassium hydroxide.

Step-by-step explanation:

Given that the crystals changed the pH of pure water to 13 after being dissolved, you could conclude the chemical is a strong base. The pH scale ranges from 0 to 14, with 7 being neutral. A pH change to 13 indicates the presence of a substance that has a much higher concentration of hydroxide ions than hydronium ions, thus making the solution highly basic (alkaline). Examples of substances that could cause such a drastic pH change include compounds like sodium hydroxide (NaOH) or potassium hydroxide (KOH), which are commonly used strong bases in a laboratory. It should be noted that acid-base indicators can be used to confirm the pH level, such as phenolphthalein which would turn pink or red in a basic solution with pH higher than 8.3, as it is a weak acid and becomes deprotonated.