Question
What is universal indicator? Give its uses.
✓
Answer
→ Acid - base indicators can be used to distinguish between acid and base. → Similarly universal indicator is used to determine the strength of acid or base and quantitative mass of ions in solution.
→ Universal indicator is a mixture of several indicators. It is used to determine the strength of acid or base.
→ Universal indicator shows different colours at different concentrations of hydrogen ions in a solution.
→ pH scale :
→ A scale for measuring concentration of hydrogen ion in a solution is called $pH$ scale.
→ In $pH$, p = Potenz (in German) = Power.
→ On the $pH$ scale we can measure $pH$ from $0$ to $14$ . $pH$ should be thought of simply as a number which indicates the acidic or basic nature of solution.
→ Higher the hydronium ion concentration, lower is the $pH$ value.
→ If $pH =7$, It shows neutral solution.
$pH <7$, It shows acidic solution.
$pH >7$, It shows basic solution.
→ As the $pH$ value increases from $7$ to $14$ , it represents an increase in $OH$ - ion concentration in the solution. So, strength of alkali increases.
→ Generally, paper impregnated with the universal indicator is used for measuring $pH$.
→ The change occurring in concentration of $H _{(a q)}^{+}$and $OH _{(a q)}^{-}$show variation in $pH$.
→ Thus strength of acid and base depend on number of $H ^{+}$and $OH ^{-}$ions produced respectively
→ If we take $1 M HCl$ and $1 M CH _3 COOH$, they produce different amount of hydrogen.
"Acids that produce more $H ^{+}$ions are called strong acids."
"Acids that produce less $H ^{+}$ions are called weak acids."
Relation between $\left[ H _3 O ^{+}\right]$and $pH$ is as follows.
$pH = pOH =14$
$pH =-\log \left[ H _3 O ^{+}\right] pOH =-\log \left[ OH ^{-}\right]$
→ Universal indicator is a mixture of several indicators. It is used to determine the strength of acid or base.
→ Universal indicator shows different colours at different concentrations of hydrogen ions in a solution.
→ pH scale :
→ A scale for measuring concentration of hydrogen ion in a solution is called $pH$ scale.
→ In $pH$, p = Potenz (in German) = Power.
→ On the $pH$ scale we can measure $pH$ from $0$ to $14$ . $pH$ should be thought of simply as a number which indicates the acidic or basic nature of solution.
→ Higher the hydronium ion concentration, lower is the $pH$ value.
→ If $pH =7$, It shows neutral solution.
$pH <7$, It shows acidic solution.
$pH >7$, It shows basic solution.
→ As the $pH$ value increases from $7$ to $14$ , it represents an increase in $OH$ - ion concentration in the solution. So, strength of alkali increases.
→ Generally, paper impregnated with the universal indicator is used for measuring $pH$.
→ The change occurring in concentration of $H _{(a q)}^{+}$and $OH _{(a q)}^{-}$show variation in $pH$.
→ Thus strength of acid and base depend on number of $H ^{+}$and $OH ^{-}$ions produced respectively
→ If we take $1 M HCl$ and $1 M CH _3 COOH$, they produce different amount of hydrogen.
"Acids that produce more $H ^{+}$ions are called strong acids."
"Acids that produce less $H ^{+}$ions are called weak acids."
Relation between $\left[ H _3 O ^{+}\right]$and $pH$ is as follows.
$pH = pOH =14$
$pH =-\log \left[ H _3 O ^{+}\right] pOH =-\log \left[ OH ^{-}\right]$
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
What are the two properties of carbon which lead to the huge number of carbon compounds we see around us?
State the exceptions of metallic and non-metallic elements.
Write the general information of the modern periodic table.
$(a)$ Why should curd and sour substances not be kept in brass and copper vessels?
$(b)$ Which gas is usually liberated when an acid reacts with a metal? Illustrate with an example. How will you test for the presence of this gas?
→$(b)$ Which gas is usually liberated when an acid reacts with a metal? Illustrate with an example. How will you test for the presence of this gas?
Write short note on: Budding###Describe briefly: Budding
The far point of a myopic person is $80 ~cm$ in front of the eye. What is the nature and power of the lens required to correct the problem?
→Draw the electron dot structure of benzene $(\text {C}_6\text {C}_6).$
→State causes of myopia. How is this defect corrected? Draw suitable diagram to show it.
difference between:
Permanent magnet and Electromagnet
Permanent magnet and Electromagnet
Write about the preparation of plasterof Paris and its uses.