Answers
Answer: pH = 1.19
Explanation:
The formula for Ka is: Ka = [H+][A-]/[HA]
where: [H+] = concentration of H+ ions
[A-] = concentration of conjugate base ions
[HA] = concentration of undissociated acid molecules
Equation of reaction: Cl₂CHCOOH ---> H+ + Cl₂CHCOO-
From the equation above, dichloroacetic acid dissociates one H+ ion for every Cl₂CHCOO- ion,
so [H+] = [Cl₂CHCOO-].
Let x represent the concentration of H+ that dissociates from HA, then [HA] = C - x where C is the initial concentration.
Substituting these values into the Ka equation:
Ka = x · x / (C -x)
Ka = x²/(C - x)
(C - x)Ka = x²
x² = CKa - Kax
x² + Kax - CKa = 0
Solve for x using the quadratic formula:
x = [-b ± √(b² - 4ac)]/2a
Note: There are two solutions for x. However only the positive value of x is used since x represents a concentration of ions in solution, and so cannot be negative.
x = [-Ka + √(Ka² + 4CKa)]/2
Substitute the values for Ka and C in the equation above:
Ka = 5.0 x 10^-2
C = 0.15 M
x = {-5.0 x 10^-2 + √[(5.0. x 10^-2)² + 4(0.15)(5.0 x 10^-2)]}/2
x = (-5.0 x 10^-2 + 1.80 x 10^-1)/2
x = 0.13/2
x = 6.50 x 10^-2
To find pH, we use the formula;
pH = -log[H+]
pH = -log(x)
pH = -log(6.50 x 10^-2)
pH = -(-1.19)
pH = 1.19
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A Se ion has a mass number of 79 and a charge of − 2 . Determine the number of neutrons, protons, and electrons in this ion.
Answers
Answer:
The free neutron has a mass of 939,565,413.3 eV/c2, or 1.674927471×10−27 kg, or 1.00866491588 u. The neutron has a mean square radius of about 0.8×10−15 m, or 0.8 fm, and it is a spin-½ fermion.
Mass: 1.67492749804(95)×10−27 kg; 939.56542052(54) MeV/c2; 1.00866491588...
Composition: 1 up quark, 2 down quarks
Electric charge: 0 e; (−2±8)×10−22 e (experimental limits)
Magnetic polarizability: 3.7(20)×10−4 fm3
Answers
Answer:
Explanation:
Hello,
In this case, for the given chemical reaction, we can notice there is a 4:2 molar ratio between the burned moles of gallium and the yielded moles of gallium sulfide, therefore, we compute them as shown below:
Then, by using the molar mass of gallium sulfide (235.64 g/mol), we directly compute the grams:
Best regards.
b.. Different kinds of elements have different kinds of atoms.
c..The protons, neutrons and electrons are different for different kinds of atoms.
d... An atom always has the same number of protons and electrons.
e... An atom always has the same number of protons and neutrons.
f.... Atoms have no mass because they are very small.
Q2 .Compare the Rutherford's model and the Bohr's model of the atom. State one similarity and one difference between them.
Q3..what observation from rutherford's gold foil experiment made him conclude that an atom has a tiny but dense nucleus that is positively charged?
Q4.. Explain why the nucleus of an atom is positively charged, while the atom is electrically neutral.
Q5...The symbols and atomic numbers of three elements are as follows:
Ne Atomic number 10
A/ Atomic number 13
K Atomic number 19
a.. identify each element from its symbol.
b.. How many protons and electrons does an atom of each element have?
c.. Draw the electronic structure of the atom of each element.
Answers
Answer:
a. false
b. true
c. false
d. false
e. false
f. false
Q2: Both have electrons orbiting around the nucleus; Bohr's model is more detailed and expands on Rutherford's
Q5:
a.
Ne = neon
Al = aluminum
K = potassium
b.
Ne = 10 electrons/protons
Al = 13 electrons/protons
K = 19 electrons/protons
Answers
Answer:
This question is incomplete
Explanation:
This question is incomplete. However, it should be noted that if the containers are compared with an equal average volume, the containers having solids will have larger masses than that containing liquid which will also have a larger mass than that containing gas. This is because solids have there molecules touching each other in compact manner which makes the molecule exert a certain combined force/mass. The molecules of liquid are also close to one another but are not compact like the solids and are hence exerting a lesser force/mass than solids. Gases have free molecules that are far apart and thus are usually the lightest when they occupy the same volume as liquids and solids.
Answers
Answer:
A precipitation reaction refers to the formation of an insoluble salt when two solutions containing soluble salts are combined. The insoluble salt that falls out of solution is known as the precipitate, hence the reaction's name.
Explanation:
Answers
Answer:
1.7 × 10⁴ J
Explanation:
Step 1: Calculate the heat required to raise the temperature of ice from -15 °C to 0°C
We will use the following expression.
Q₁ = c(ice) × m × ΔT
Q₁ = 2.03 J/g.°C × 25 g × [0°C - (-15°C)] = 7.6 × 10² J
Step 2: Calculate the heat required to melt 25 g of ice
We will use the following expression.
Q₂ = C(fusion) × m
Q₂ = 80. cal/g × 25 g × 4.184 J/1 cal = 8.4 × 10³ J
Step 3: Calculate the heat required to raise the temperature of water from 0°C to 75 °C
We will use the following expression.
Q₃ = c(water) × m × ΔT
Q₃ = 4.184 J/g.°C × 25 g × (75°C - 0°C) = 7.8 × 10³ J
Step 4: Calculate the total heat required
Q = Q₁ + Q₂ + Q₃
Q = 7.6 × 10² J + 8.4 × 10³ J + 7.8 × 10³ J = 1.7 × 10⁴ J