Answer:
4.09×10⁻³ is the mole fraction of sucrose
Explanation:
Mole fraction = Moles of solute or solvent/ Total moles
Let's convert the mass to moles (mass / molar mass)
38.6 g / 342 g/m = 0.113 moles of sucrose
495 g / 18 g/m = 27.5 moles of water
Total moles = 0.113 m + 27.5 m = 27.0613 moles
Mole fraction of sucrose = Moles of sucrose / Total moles
0.113 m / 27.0613 moles = 4.09×10⁻³
Answer:
Example
0.5 mol of sodium hydroxide is dissolved in 2 dm3 of water. Calculate the concentration of the sodium hydroxide solution formed.
Concentration =
Concentration = 0.25 mol/dm3
Volume units
Volumes used in concentration calculations must be in dm3, not in cm3. It is useful to know that 1 dm3 = 1000 cm3. This means:
divide by 1000 to convert from cm3 to dm3
multiply by 1000 to convert from dm3 to cm3
For example, 250 cm3 is 0.25 dm3 (250 ÷ 1000). It is often easiest to convert from cm3 to dm3 before continuing with a concentration calculation.
Question
100 cm3 of dilute hydrochloric acid contains 0.02 mol of dissolved hydrogen chloride. Calculate the concentration of the acid in mol/dm3.
Reveal answer
Converting between units
The relative formula mass of the solute is used to convert between mol/dm3 and g/dm3:
to convert from mol/dm3 to g/dm3, multiply by the relative formula mass
to convert from g/dm3 to mol/dm3, divide by the relative formula mass
Remember: the molar mass is the Ar or Mr in grams per mol.
Example
Calculate the concentration of 0.1 mol/dm3 sodium hydroxide solution in g/dm3. (Mr of NaOH = 40)
Concentration = 0.1 × 40
= 4 g/dm3
Answer: hydroxide ions
Explanation:
According to the Arrhenius concept, an acid is a substance that ionizes in the water to give hydronium ion or hydrogen ion and a bases is a substance that ionizes in the water to give hydroxide ion .
According to the Bronsted Lowry conjugate acid-base theory, an acid is defined as a substance which donates protons and a base is defined as a substance which accepts protons.
According to the Lewis concept, an acid is defined as a substance that accepts electron pairs and base is defined as a substance which donates electron pairs.
As KOH can give hydroxide ions on dissociation , it is considered as arrhenius base.
Answer:
It will be denatured.
Explanation:
Salivary amylase works best at pH 6.8.
At pH 2.5, its activity will decrease enormously as it becomes denatured by the high acidity of the stomach contents.
