Answer:
the awnser is kilograms(Kg)
Answer : The value of 'x' for this expression is, 5.59
Explanation :
The given expression is:
Now we have to determine the value of 'x' by solving the above expression.
Thus, the value of 'x' for this expression is, 5.59
Be
Ca
Ba
Sr
Answer:
none
Explanation:
it's Fr. which is francium.
Explanation:
An atomic radius is defined to be one-half the distance between the nuclei of two atoms, assuming a spherical atom since, according to the quantum mechanical model of the atom, electrons are located within a probability cloud surrounding the nucleus which has no sharp boundary.
Notice that, in general, there are two main trends of atomic radii in the Periodic Table of Elements.
The first trend illustrates that atomic radii increase when going down a group in the periodic table. This is because when moving downwards in a group, every subsequent atom gains an additional principal energy level, which leads to electron shielding. Electron shielding refers to the decreased attraction between the electrons that occupy the higher principal energy level and the nucleus of the atom due to the shielding of electrons in the lower principal energy level.
The second trend outlines that atomic radii decrease when going across the period from left to right. For elements within a period, individual electrons occupy the same principal energy level. Likewise, when an electron is added, a new proton is also added to the nucleus, providing the nucleus with a stronger positive charge and hence leading to a higher effective nuclear charge. This increase in nuclear attraction pulls the electrons closer towards the nucleus, leading to a decrease in atomic radius.
Therefore, given the option between beryllium, calcium, barium, and strontium, the element with the largest atomic radius is barium since all the elements given are in Group II, however, barium is the element furthest down the group and therefore have electrons occupying the highest principal energy level compared to other elements.
O neutrons
O Neither... An atom isn't neutral!
Taking into account the constitution of an atom, an atom is neutral because it has the same number of protons as it has electrons.
An atom is the smallest constituent unit of ordinary matter that has the properties of a chemical element.
Every atom consists of a nucleus in which neutrons and protons meet and energy levels where electrons are located.
The neutron is an electrically neutral subatomic particle, while the proton has a positive electrical charge. Electrons have a negative charge, move around the nucleus at different energy levels and are attracted to protons, positive in the atom through electromagnetic force.
An atom is considered electrically neutral when it has the same number of positive and negative charges. That is, an electrically neutral atom has the same number of protons (with a positive charge) and electrons (with a negative charge).
In summary, an atom is neutral because it has the same number of protons as it has electrons.
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The pH of the solution in the titration of 30 mL of 0.030 M NH₃ with 0.025 M HCl, is:
a) pH = 10.86
b) pH = 9.66
c) pH = 9.15
d) pH = 7.70
e) pH = 5.56
f) pH = 3.43
Initially, the pH of the solution is given by the dissociation of NH₃ in water.
NH₃ + H₂O ⇄ NH₄⁺ + OH⁻ (1)
The constant of the above reaction is:
(2)
At the equilibrium, we have:
NH₃ + H₂O ⇄ NH₄⁺ + OH⁻ (3)
0.030 M - x x x
After solving for x and taking the positive value:
x = 7.18x10⁻⁴ = [OH⁻]
Now, we can calculate the pH of the solution as follows:
Hence, the initial pH is 10.86.
After the addition of HCl, the following reaction takes place:
NH₃ + HCl ⇄ NH₄⁺ + Cl⁻ (4)
We can calculate the pH of the solution from the equilibrium reaction (3).
(5)
The number of moles of NH₃ (nb) and NH₄⁺ (na) are given by:
(6)
(7)
The concentrations are given by:
(8)
(9)
After entering the values of Ca and Cb into equation (5) and solving for x, we have:
x = 4.54x10⁻⁵ = [OH⁻]
Then, the pH is:
Hence, the pH is 9.66.
We can find the pH of the solution from the reaction of equilibrium (3).
The concentrations are (eq 8 and 9):
After solving the equation (5) for x, we have:
x = 1.40x10⁻⁵ = [OH⁻]
Then, the pH is:
So, the pH is 9.15.
We can find the pH of the solution from reaction (3).
After solving the equation (5) for x, we have:
x = 5.013x10⁻⁷ = [OH⁻]
Then, the pH is:
So, the pH is 7.70.
Since all the NH₃ reacts with the HCl added, the pH of the solution is given by the dissociation reaction of the NH₄⁺ produced in water.
At the equilibrium, we have:
NH₄⁺ + H₂O ⇄ NH₃ + H₃O⁺
Ca - x x x
(10)
We can find the acid constant as follows:
Where Kw is the constant of water = 10⁻¹⁴
The concentration of NH₄⁺ is:
After solving the equation (10) for x, we have:
x = 2.78x10⁻⁶ = [H₃O⁺]
Then, the pH is:
Hence, the pH is 5.56.
Now, the pH is given by the concentration of HCl that remain in solution after reacting with NH₃ (HCl is in excess).
Therefore, the pH is 3.43.
Find more about pH here:
I hope it helps you!
Answer:
a)10.87
b)9.66
c)9.15
d)7.71
e) 5.56
f) 3.43
Explanation:
tep 1: Data given
Volume of 0.030 M NH3 solution = 30 mL = 0.030 L
Molarity of the HCl solution = 0.025 M
Step 2: Adding 0 mL of HCl
The reaction: NH3 + H2O ⇔ NH4+ + OH-
The initial concentration:
[NH3] = 0.030M [NH4+] = 0M [OH-] = OM
The concentration at the equilibrium:
[NH3] = 0.030 - XM
[NH4+] = [OH-] = XM
Kb = ([NH4+][OH-])/[NH3]
1.8*10^-5 = x² / 0.030-x
1.8*10^-5 = x² / 0.030
x = 7.35 * 10^-4 = [OH-]
pOH = -log [7.35 * 10^-4]
pOH = 3.13
pH = 14-3.13 = 10.87
Step 3: After adding 10 mL of HCl
The reaction:
NH3 + HCl ⇔ NH4+ + Cl-
NH3 + H3O+ ⇔ NH4+ + H2O
Calculate numbers of moles:
Moles of NH3 = 0.030 M * 0.030 L = 0.0009 moles
Moles HCl = 0.025 M * 0.010 L = 0.00025 moles
Moles NH4+ = 0 moles
Number of moles at the equilibrium:
Moles NH3 = 0.0009 -0.00025 =0.00065 moles
Moles HCl = 0
Moles NH4+ = 0.00025 moles
Concentration at the equilibrium:
[NH3]= 0.00065 moles / 0.040 L = 0.01625M
[NH4+] = 0.00625 M
pOH = pKb + log [NH4+]/[NH3]
pOH = 4.75 + log (0.00625/0.01625)
pOH = 4.34
pH = 9.66
Step 3: Adding 20 mL of HCl
Calculate numbers of moles:
Moles of NH3 = 0.030 M * 0.030 L = 0.0009 moles
Moles HCl = 0.025 M * 0.020 L = 0.00050 moles
Moles NH4+ = 0 moles
Number of moles at the equilibrium:
Moles NH3 = 0.0009 -0.00050 =0.00040 moles
Moles HCl = 0
Moles NH4+ = 0.00050 moles
Concentration at the equilibrium:
[NH3]= 0.00040 moles / 0.050 L = 0.008M
[NH4+] = 0.01 M
pOH = pKb + log [NH4+]/[NH3]
pOH = 4.75 + log (0.01/0.008)
pOH = 4.85
pH = 14 - 4.85 = 9.15
Step 4: Adding 35 mL of HCl
Calculate numbers of moles:
Moles of NH3 = 0.030 M * 0.030 L = 0.0009 moles
Moles HCl = 0.025 M * 0.035 L = 0.000875 moles
Moles NH4+ = 0 moles
Number of moles at the equilibrium:
Moles NH3 = 0.0009 -0.000875 =0.000025 moles
Moles HCl = 0
Moles NH4+ = 0.000875 moles
Concentration at the equilibrium:
[NH3]= 0.000025 moles / 0.065 L = 3.85*10^-4M
[NH4+] = 0.000875 M / 0.065 L = 0.0135 M
pOH = pKb + log [NH4+]/[NH3]
pOH = 4.75 + log (0.0135/3.85*10^-4)
pOH = 6.29
pH = 14 - 6.29 = 7.71
Step 5: adding 36 mL HCl
Calculate numbers of moles:
Moles of NH3 = 0.030 M * 0.030 L = 0.0009 moles
Moles HCl = 0.025 M * 0.036 L = 0.0009 moles
Moles NH4+ = 0 moles
Number of moles at the equilibrium:
Moles NH3 = 0.0009 -0.0009 =0 moles
Moles HCl = 0
Moles NH4+ = 0.0009 moles
[NH4+] = 0.0009 moles / 0.066 L = 0.0136 M
Kw = Ka * Kb
Ka = 10^-14 / 1.8*10^-5
Ka = 5.6 * 10^-10
Ka = [NH3][H3O+] / [NH4+]
Ka =5.6 * 10^-10 = x² / 0.0136
x = 2.76 * 10^-6 = [H3O+]
pH = -log(2.76 * 10^-6)
pH = 5.56
Step 6: Adding 37 mL of HCl
Calculate numbers of moles:
Moles of NH3 = 0.030 M * 0.030 L = 0.0009 moles
Moles HCl = 0.025 M * 0.037 L = 0.000925 moles
Moles NH4+ = 0 moles
Number of moles at the equilibrium:
Moles NH3 = 0.0009 -0.000925 =0 moles
Moles HCl = 0.000025 moles
Concentration of HCl = 0.000025 moles / 0.067 L = 3.73 * 10^-4 M
pH = -log 3.73*10^-4= 3.43
A. The colors in the computer display are the result of substances
that glow.
B. By clicking a mouse, you can select an object or text on a
computer screen.
C. Eye stress can be reduced by sitting a certain distance from the
Screen.
D. You are able to play video games by moving your body instead of a
joystick
A way in which chemistry affects how To use a computer is The colors in the computer display are the result of substances that glow. Option A
In modern computers, the display technology commonly used is Liquid Crystal Display (LCD) or Light Emitting Diode (LED) technology. These displays rely on the principles of chemistry to produce the colors that we see on the screen.
In LCD screens, tiny liquid crystal cells are controlled by an electric current, which causes them to either block or allow the passage of light. Each cell represents a pixel on the screen, and by controlling the intensity of light passing through each pixel, different colors can be produced.
The liquid crystals used in LCD screens are organic compounds that exhibit unique optical properties, allowing them to manipulate light in a controlled manner.
LED screens, on the other hand, use arrays of light-emitting diodes to generate light. These diodes are made of semiconducting materials, often composed of compounds like gallium, arsenic, and phosphorus. When an electric current passes through these compounds, they emit light of a specific wavelength, resulting in the different colors displayed on the screen.
So, the colors we see on a computer display are a direct result of the chemical properties and behavior of the substances used in the LCD or LED technology. Chemistry plays a crucial role in the design and functionality of computer displays, enabling us to view vibrant and accurate colors while using our computers.
Option A
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