Answer:
81°C.
Explanation:
To solve this problem, we can use the relation:
<em>Q = m.c.ΔT,</em>
where, Q is the amount of heat released from water (Q = - 1200 J).
m is the mass of the water (m = 20.0 g).
c is the specific heat capacity of water (c of water = 4.186 J/g.°C).
ΔT is the difference between the initial and final temperature (ΔT = final T - initial T = final T - 95.0°C).
∵ Q = m.c.ΔT
∴ (- 1200 J) = (20.0 g)(4.186 J/g.°C)(final T - 95.0°C ).
(- 1200 J) = 83.72 final T - 7953.
∴ final T = (- 1200 J + 7953)/83.72 = 80.67°C ≅ 81.0°C.
<em>So, the right choice is: 81°C.</em>
Answer:
Explanation:
a )
pH = - log[ H⁺]
8.26 = - log[ H⁺]
[ H⁺] = 10⁻⁸°²⁶ mole / l
= 5.49 x 10⁻⁹ moles / l
[ H⁺] [OH⁻] = 10⁻¹⁴
[OH⁻] = 10⁻¹⁴ / 5.49 x 10⁻⁹
= .182 x 10⁻⁵ moles / l
b )
10.25 = - log[ H⁺]
[ H⁺] = 10⁻¹⁰°²⁵ mole / l
= 5.62 x 10⁻¹¹ moles / l
[ H⁺] [OH⁻] = 10⁻¹⁴
[OH⁻] = 10⁻¹⁴ / 5.62 x 10⁻¹¹
= .178 x 10⁻³ moles / l
c )
4.65 = - log[ H⁺]
[ H⁺] = 10⁻⁴°⁶⁵ mole / l
= 2.24 x 10⁻⁵ moles / l
[ H⁺] [OH⁻] = 10⁻¹⁴
[OH⁻] = 10⁻¹⁴ / 2.24 x 10⁻⁵
= .4464 x 10⁻⁹ moles / l
There are a number of ways to express concentration
of a solution. This includes molarity. Molarity is expressed as the number of
moles of solute per volume of the solution. The concentration of the solution
is calculated as follows:
Molarity = 2.0 mole / L solution
<span>2.0 mole / L solution ( 0.50 Liters ) = 1 mole solute</span>
<span>The correct answer is the third option. One mole of solute needed to make 0.50 liters of 2M solution.</span>
