Answer:
Molarity = 0.95 mol/dm³
Explanation:
Given data:
Volume of H₂SO₄ = 15.8 cm³
Volume of NaOH = 20 cm³
Concentration of NaOH = 1.5 mol/dm³
Concentration of H₂SO₄ = ?
Solution:
Chemical equation:
NaOH + H₂SO₄ → Na₂SO₄ + H₂O
First of all we will calculate the number of moles of NaOH and for that we will convert the units first,
Volume = 20 cm³/1000 = 0.02 L
Concentration of NaOH = 1.5 mol/dm³
1 mol/dm³ = 1 mol/L
Concentration of NaOH = 1.5 mol/L
Number of moles of NaOH:
Molarity = number of moles / volume in L
1.5 M = number of moles / 0.02 L
Number of moles = 1.5 M ×0.02 L
Number of moles = 0.03 mol
Now we will compare the moles of NaOH and H₂SO₄
NaOH : H₂SO₄
2 : 1
0.03 : 1/2×0.03 = 0.015 mol
Concentration of H₂SO₄:
Volume of H₂SO₄:
15.8 cm³/1000 = 0.0158 L
Molarity = number of moles / volume in L
Molarity = 0.015 mol / 0.0158 L
Molarity = 0.95 mol/L
1 mol/L = 1 mol/dm³
Molarity = 0.95 mol/dm³
The curved top of a liquid is the meniscus
Answer:
See explanation below
Explanation:
The melting point (the temperature that it changes from solid to liquid) of a pure substance depends on its mass, the forces between its molecules, and the pressure of the system.
The melting point, or the freezing point, of a mixture, is a temperature between the melting point of its components. Salt has a huge negative melting point, so when it is added to the water, the melting point decreases from 0ºC to -21ºC approximately.
So, the water will only freeze again if the temperature becomes below -21ºC which is very difficult to happen.
