<span>A compound is a pure substance composed of two or more different atoms chemically bonded to one another. A compound can be destroyed by chemical means. It might be broken down into simpler compounds, into its elements or a combination of the two.</span>
Answer: Vertebrates move by the actions of muscles on bones. Tendons attach many skeletal muscles across joints, allowing muscle contraction to move the bones across the joint.
Explanation:
Answer:
a. 0.40
b. 0 .62 mol HCl
c. 0.29 mol HCl
Explanation:
Lets call A⁻ the molar concentration of the weak base A⁻, and HA the acid concentration of HA
a. pH = pKa
from Henderson-Hasselbach equation for buffer solutions:
pH = pKa - log(( A⁻/HA))
we can see that pH = Pka when the log(( A⁻/HA)) is 0 which is the case for the log 1 hence
A⁻ =HA and
Ka= H⁺ x A ⁻/ HA
Now for the equilibrium of the weak acid we have
R HA================== H⁺ + A⁻
Initially 0.80 0 0
Change -x + x + x
Equilibrium 0.80 - x x x
Since x = A⁻ and HA = 0.80- x
x/ (0.80-x) =1
x = 0.80 -x 2x = 0.80
x = 0.40
b. From the Henderson-Hasselbach eqn:
pH = pKa - log ((A⁻/HA))
4.20-4.74 = log ((0 .80-x)/x) (the negative log of A⁻/HA is the same as log HA/A⁻)
-0.54 = log ((0.80-x)/x)
0.29 = (0.80-x)/x
0.29 x = 0.80 - x
1.29 x = 0.80 moles HCL
x = 0.62
c. pH= 5.00
Using the same relationships as in b.
5.00-4.74 = log ((0.80-x)/x)
1.80 =( 0.80 - x) /x
2.8 x = 0.80
x = 0.29
0.29 mol HCl needed
Answer:
Explanation:Copper can be extracted from its ore by: Underground: sinking a vertical shaft into the Earth to an appropriate depth and driving horizontal tunnels into the ore. ... The ore is treated with dilute sulfuric acid. This trickles slowly through the ore dissolving copper to form copper sulfate.
Answer:
0.165kJ
Explanation:
Formula to use for such a question is;
Energy = number of mole x molar gas constant x change in temperature
Number of mole = reacting mass of mercury / molar mass of mercury = 45.30/200.58 = 0.226moles
Change in temperature = final temperature - initial temperature = 30 - (-59) =30 + 59 = 89 Kelvin
E = nRT = 0.226 x 8.314 x 89
Energy = 165.35Joules
Energy in kJ = 165.35/1000 = 0.165kJ