Answer:
a) C6H5COOH + H2O ↔ H3O+ + C6H5COO-
b) [ H3O+ ] = 2.517 E-3 M
c) pH = 2.599
Explanation:
a) balanced equation:
C6H5COOH + H2O ↔ H3O+ + C6H5COO-
⇒ Ka = ( [ H3O+ ] * [ C6H5COO- ] ) / [ C6H5COOH ] = 6.5 E-5
mass balance:
0.10 m = [ C6H5COO- ] + [ C6H5COOH ].....(1)
charge balance:
[ H3O+ ] = [ C6H5COO- ] + [ OH- ] .......[ OH- ] : comes from water, it's not significant
⇒ [ H3O+ ] = [ C6H5COO- ] .........(2)
b) (2) in (1):
⇒ 0.10 M = [ H3O+ ] + [ C6H5COOH ]
⇒ [ C6H5COOH ] = 0.10 - [ H3O+ ]
⇒ Ka = [ H3O+ ]² / ( 0.1 - [ H3O+ ] ) = 6.5 E-5
⇒ [ H3O+ ]² + 6.5 E-5 [ H3O+ ] - 6.5 E-6 = 0
⇒ [ H3O+ ] = 2.517 E-3 M
c) pH = - log [ H3O+ ]
⇒ pH = - Log ( 2.517 E-3 )
⇒ pH = 2.599
Answer: The force on the firefly
The unfortunate firefly hitting the bus does not change the velocity of the bus very much. Technically there is a change, but it's so very small and miniscule that it barely registers. To any casual observer not paying very close attention, they don't notice anything at all. So effectively the force on the firefly is a lot greater since the firefly got the worst end of the deal.
So in short, we look at the velocity of each object and see which velocity changed the most. In this case, the firefly's velocity changed from whatever speed it was flying to 0 when it stops flying all together. That's why the force is greater on the bug.
Answer:
72
Explanation:
The pattern here may be hard to find at first, but it's this: the number in the middle of the triangle = (number at lower left corner of triangle x number at upper vertex of triangle) + (number at upper vertex of triangle x number at lower right corner of triangle).
Thus, for the missing value...
Missing value = (3x8) + (8x6) = 24+48 = 72.
Could you tell me what concept in chemistry relates to this? I'm interested.
Also check out stylesben's answer. Seems like there's several ways of doing this.
80 equals the mass number. In the periodic table, the atomic number of Bromine is 35. The atomic number equals the number of protons.
80-35= number of neutrons (mass-protons)
So, we have P=35 N=45
Furthermore, since the atom is neutral that must mean that the number of electrons equals the number of protons.
e=35
Answer:
5.45*10⁻⁴ moles of silane gas (SiH₄) are present in 8.68 mL measured at 18°C and 1.50 atm.
Explanation:
An ideal gas is a theoretical gas that is considered to be composed of point particles that move randomly and do not interact with each other. Gases in general are ideal when they are at high temperatures and low pressures.
An ideal gas is characterized by three state variables: absolute pressure (P), volume (V), and absolute temperature (T). The relationship between them constitutes the ideal gas law, an equation that relates the three variables if the amount of substance, number of moles n, remains constant and where R is the molar constant of the gases:
P * V = n * R * T
In this case:
- P= 1.5 atm
- V= 8.68 mL= 0.00868 L (being 1000 mL= 1 L)
- n= ?
- R= 0.082
- T= 18 C= 291 K (being 0 C= 273 K)
Replacing:
1.5 atm* 0.00868 L= n* 0.082 *291 K
Solving:
n= 5.45*10⁻⁴ moles
<u><em>5.45*10⁻⁴ moles of silane gas (SiH₄) are present in 8.68 mL measured at 18°C and 1.50 atm.</em></u>
