When the amount of heat gained = the amount of heat loss
so, M*C*ΔTloses = M*C* ΔT gained
when here the water is gained heat as the Ti = 25°C and Tf= 28°C so it gains more heat.
∴( M * C * ΔT )W = (M*C*ΔT) Al
when Mw is the mass of water = 100 g
and C the specific heat capacity of water = 4.18
and ΔT the change in temperature for water= 28-25 = 3 ° C
and ΔT the change in temperature for Al = 100-28= 72°C
and M Al is the mass of Al block
C is the specific heat capacity of the block = 0.9
so by substitution:
100 g * 4.18*3 = M Al * 0.9*72
∴ the mass of Al block is = 100 g *4.18 / 0.9*72
= 19.35 g
1 mole = 6.022x10²³ of anything. The number 6.022x10²³ is known as Avogadro's number. Avogadro's number is not a mass, it is just a unit of measure. Other units of measure include: 1 pair (2), 1 dozen (12), a baker's dozen (13), et. al. 1 mole is similar in that it simply represents a certain number of things; specifically, Avogadro's number of things.
Since we know 1 mole is not a mass, the first two options can be eliminated. On observing the third option, it cannot be correct because, as we said, 1 mole is equal to Avogadro's number—not an atom of a given substance.
<h3>
Answer:</h3>
Amount of substance present in Avogadro's number of particles of the substance
Answer:
Explanation:
Caffeine is a weak base with pKb = 10.4
Kb = 10⁻¹⁰°⁴ = 3.98 x 10⁻¹¹
molecular weight of caffeine = 194.2
455 x 10⁻³ g / L = 455 x 10⁻³ / 194.2 moles / L
concentration of given solution a = 2.343 x 10⁻³ M
Let the caffeine be represented by B .
B + H₂O = BH + OH⁻
a - x x x
x² / ( a - x ) = Kb
x² / ( a - x ) = 3.98 x 10⁻¹¹
x is far less than a so a -x is almost equal to a
x² = 3.98 x 10⁻¹¹ x 2.343 x 10⁻³ = 9.32 x 10⁻¹⁴
x = 3.05 x 10⁻⁷
[ OH⁻ ] = 3.05 x 10⁻⁷
pOH = - log ( 3.05 x 10⁻⁷ )
= 7 - log 3.05
= 7 - 0.484 = 6.5
pH = 14 - 6.5 = 7.5
When a volume of 60.0 mL of 0.200 M HBr is mixed with a volume of 30.0 mL of 0.400 M CH3NH2, The pH value is mathematically given as
pH=10.64
<h3>What is
the pH value when 60.0 mL of 0.200 M HBr is mixed with 30.0 mL of 0.400 M CH₃NH₂?</h3>
Question Parameters:
The pH when 60.0 mL of 0.200 M HBr
30.0 mL of 0.400 M CH₃NH₂ (Kb = 4.4 × 10^{-4}).
Generally, the equation for the Chemical Reaction is mathematically given as
H Br + H_3C NH_2----- > CH_3 NH_3 Br
Therefore
oH=p^{kb}+-log
OH=-log(4.4*10^{-4})+
OH=3.36
In conclusion, The equation pH value
pH+OH=14
Therefore
pH+=14-3.36
pH=10.64
Read more about Chemical Reaction
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