Ph Scale Flashcards
What does the pH scale measure
pH scale measures the acidity or alkalinity of a solution based on the concentration of hydrogen ions (H+)
What’s the pH range of acidic solution
Less than 7
What’s the pH of a neutral solution
pH 7
What’s the pH range of an alkaline solution
Greater than 7
What ion is present in all acidic solutions
Hydrogen ions (H+)
What ion is present in all alkaline solutions?
Hydroxide ions (OH- )
How does the concentration of H+ ions change with each pH unit?
Each pH unit change represents a tenfold change in H+ ion concentration
General ructions for a neutralisation reaction
Acid+Base ____ Salt+Water
Whats the product of reaction between hydrochloric acid and sodium hydroxide
Sodium chloride and water
What’s the pH of the solution after a complete neutralisation reaction
pH 7
Name 3 ways to measure a pH
Universal indicator, pH metres and litmus paper
What colour does universal indicator turn in a strong acid
Red
What’s the advantage of using a pH metre over an indicator
A pH metre provides a precise numerical value
What’s the difference between strong ans weak acid
Strong acid fully ionize in water,while weak acids only partially ionize
Which will have a lower pH: a strong or a weak acid of the same concentration
A strong acid
Which solution has the highest concentration of H+ ions
pH 2
A solution has a pH of 3. Is it acidic,neutral, or alkaline
Acidic
A solution has a pH of 8. What type of solution is it
Weakly alkaline
Describe how u could measure the pH of a solution in a laboratory
Use a universal indicator to observe the colour change or a pH probe to measure the numerical pH value.
Describe how u could measure the pH of a solution in a laboratory
Use a universal indicator to observe the colour change or a pH probe to measure the numerical pH value.
A student adds sodium hydroxide to hydrochloric acid, and the pH changes from 2 to 7. What type of reaction has occurd
Neutralisation
Explain why strong acids have lower pH values than weak acids of the same concentration.
Strong acids fully ionize in water, releasing more H⁺ ions into the solution, which lowers the pH. Weak acids only partially ionize, so the concentration of H⁺ ions is lower, resulting in a higher pH.
A student measures the pH of two solutions: hydrochloric acid (HCl) and ethanoic acid (CH₃COOH). Both have the same concentration. Explain why HCl has a lower pH
HCl is a strong acid and fully ionizes in solution, producing more H⁺ ions. Ethanoic acid is a weak acid and only partially ionizes, so it produces fewer H⁺ ions.
A solution of pH 6 is diluted 10 times. What is the new pH?
The new pH is closer to 7, as dilution reduces the concentration of H⁺ ions.
What does a pH of 7 indicate about a solution?
Neutral.
he colors observed are red, green, and purple. State the approximate pH for each color and classify the solutions as acidic, neutral, or alkaline.
Red: pH 1 (acidic).
Green: pH 7 (neutral).
Purple: pH 13 (alkaline).
