A car rolls down a ramp. What is the force acting on the car that causes the movement down the ramp? A) acceleration B) centripe
1 answer:
You might be interested in
Answer:
.
Explanation:
Carbon and hydrogen are the only two elements in a hydrocarbon. When a hydrocarbon combusts completely in excess oxygen, the products would be and
. The
and
would come from the hydrocarbon, while the
atoms would come from oxygen.
Look up the relative atomic mass of these three elements on a modern periodic table:
:
.
:
.
:
.
Calculate the molar mass of and
:
.
Calculate the number of moles of molecules in
of
:
.
Similarly, calculate the number of moles of molecules in
of
:
.
Note that there is one carbon atom in every molecule. Approximately
of
molecules would correspond to the same number of
atoms. That is:
.
On the other hand, there are two hydrogen atoms in every molecule. approximately
of
molecules would correspond to twice as many
atoms. That is:
.
The ratio between the two is: .
The empirical formula of a compound gives the smallest whole-number ratio between the elements. For this hydrocarbon, the empirical formula would be .
Answer:
- pKa = 7.46
Explanation:
<u>1) Data:</u>
a) Hypochlorous acid = HClO
b) [HClO} = 0.015
c) pH = 4.64
d) pKa = ?
<u>2) Strategy:</u>
With the pH calculate [H₃O⁺], then use the equilibrium equation to calculate the equilibrium constant, Ka, and finally calculate pKa from the definition.
<u>3) Solution:</u>
a) pH
- pH = - log [H₃O⁺]
- 4.64 = - log [H₃O⁺]
b) Equilibrium equation: HClO (aq) ⇄ ClO⁻ (aq) + H₃O⁺ (aq)
c) Equilibrium constant: Ka = [ClO⁻] [H₃O⁺] / [HClO]
d) From the stoichiometry: [CLO⁻] = [H₃O⁺] = 2.29 × 10 ⁻⁵ M
e) By substitution: Ka = (2.29 × 10 ⁻⁵ M)² / 0.015M = 3.50 × 10⁻⁸ M
f) By definition: pKa = - log Ka = - log (3.50 × 10 ⁻⁸) = 7.46