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Gala2k [10]
3 years ago
8

When thermal

Chemistry
1 answer:
inn [45]3 years ago
8 0
I just had it it’s was c
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Which metal atom below cannot form a cation of several different charges?
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Answer is: Ba (barium).
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4 0
4 years ago
Calculate the pH of a solution containing a caffeine concentration of 455 mg/L . Express your answer to one decimal place.
Marrrta [24]

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  

               

7 0
3 years ago
suppose the mass spectrum of a hypothetical monatomic element X contains a signal at mass number 13 and another of identical hei
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Which of these substances are elements?
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An element is a species of atom that has the same amounts of electrons and protons in their nuclei. To know which of these substances are elements, we can look it up in the periodic table of elements. The elements are as follows:

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8 0
3 years ago
Read 2 more answers
What is molarity???????
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Molarity is a term that applies to the amount of Moles of solute, per each litre of the solution. 
4 0
3 years ago
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