Answer:
Check the explanation
Explanation:
1)
Atomic number of Se = 34
So, number of proton = 34
use:
charge = number of proton - number of electron
-2 = 34 - number of electron
number of electron = 36
number of neutron = mass number - atomic number
= 78 - 34
= 44
Answer:
44
34
36
2)
number of proton = mass number - number of neutron
= 65 - 36
= 29
29 is atomic number for Cu
use:
charge = number of proton - number of electron
+1 = 29 - number of electron
number of electron = 28
Answer:
Cu
29
28
3)
Atomic number is 36 for Kr
use:
charge = number of proton - number of electron
= 36 - 36
= 0
use:
mass number = number of proton + number of neutron
= 36 + 42
= 78
Answer:
Kr
78
0
What is the total oxidation state of the fluorine atoms
Answer:
-1
Explanation:
What is a noble gas electron configuration of bismuth?
Answer:
It is [Xe] 4f14 5d10 6s2 6p3 and its atomic number is 83
A reaction starts with 20.0 g of lithium hydroxide (LiOH) and actually produces 31.0 g of lithium chloride (LiCl), what is the percent yield? (Hint: First calculate the theoretical yield of lithium chloride (LiCl))
64.5%
88.6%
81.5%
92.8%
Answer:
87.6 %
Explanation:
Step 1: Write the balanced equation
LiOH + KCl ⇒ LiCl + KOH
Step 2: Calculate the theoretical yield of LiCl
We will use the following relations:
The molar mass of LiOH is 23.95 g/mol.The molar ratio of LiOH to LiCl is 1:1.The molar mass of LiCl is 42.39 g/mol.The theoretical yield of LiCl from 20.0 g of LiOH is:
[tex]20.0gLiOH \times \frac{1molLiOH}{23.95gLiOH} \times \frac{1molLiCl}{1molLiOH} \times \frac{42.39gLiCl}{1molLiCl} = 35.4gLiCl[/tex]
Step 3: Calculate the percent yield of LiCl.
We will use the following expression.
[tex]\%yield = \frac{real\ yield}{theoretical\ yield} \times 100\% = \frac{31.0g}{35.4g} \times 100\% = 87.6 \%[/tex]
Answer:
88.6%
Explanation:
Hello,
In this case, considering the given reaction, we notice a 1:1 molar relationship between lithium hydroxide (molar mass=23.95 g/mol) and lithium chloride (molar mass=42.394 g/mol), for that reason, we are able to compute the theoretical yield of lithium chloride by stoichiometry:
[tex]m_{LiCl}^{theoretical}=20.0gLiOH*\frac{1molLiOH}{23.95gLiOH}*\frac{1molLiCl}{1molLiOH} *\frac{42.394 gLiCl}{1molLiCl}=35.4gLiCl[/tex]
Next, by knowing the actual yield of 31.0 g, we compute the percent yield as:
[tex]Y=\frac{m_{LiCl}^{actual}}{m_{LiCl}^{theoretical}} *100\%=\frac{31.0g}{35.4g}*100\%\\ \\Y=87.6\%[/tex]
Therefore, among the given, the answer should be 88.6%
Best regards.
Plants remove carbon to the atmosphere during
Answer:
respiration
Explanation:
Plants give out carbon dioxide not only at night but during the day too. It happens because of the process of respiration in which plants take in oxygen and give out carbon dioxide. As soon as the sun rises another process called photosynthesis starts, in which carbon dioxide is taken in and oxygen is given out.
Plants use photosynthesis to capture carbon dioxide and then release half of it into the atmosphere through respiration. Plants also release oxygen into the atmosphere through photosynthesis
In a titration, 100 mL of 0.026 M HCl (aq) is neutralized by 13 mL of KOH(aq). Calculate the molarity of KOH (aq).
Answer:
0.2M
Explanation:
Step 1:
Data obtained from the question.
Volume of acid (Va) = 100mL
Molarity of the acid (Ma) = 0.026 M
Volume of base (Vb) = 13mL
Molarity of the base (Mb) =..?
Step 2:
The balanced equation for the reaction. This is given below:
HCl + KOH —> KCl + H2O
From the balanced equation above,
The mole ratio of the acid (nA) = 1
The mole ratio of the base (nB) = 1
Step 3:
Determination of the molarity of the base, KOH. This can be obtained as follow:
MaVa/MbVb = nA/nB
0.026 x100 / Mb x 13 = 1
Cross multiply to express in linear form
Mb x 13 = 0.026 x 100
Divide both side by 13
Mb = 0.026 x 100 / 13
Mb = 0.2M
Therefore, the molarity of the base, KOH is 0.2M
Answer:
0.2M
Explanation:
KOH(aq) + HCl(aq) ⇒ KCl(aq) + H2O(l)
We express the moles of analyte (HCl) and titrant based (KOH) on their molar concentration:
M1 * V1 = M2 * V2
The molarity of the solution is calculated with the following equation:
M2 = V1 x M1 / V2
Where:
V2 = valued sample volume
V1 = volume of titrant consumed (measured with the burette)
M1 = concentration of titrant solution
M2 = concentration of sample
M2 = 100mL * 0.026M / 13mL = 0.2M
What is the poH of a
6.5 x 10-12 M OH solution?
pOH = [?]
Answer:
[tex]pOH=11.2[/tex]
Explanation:
Hello,
In this case, by knowing that the pOH is defined in terms of the concentration of OH⁻ as shown below:
[tex]pOH=-log([OH^-])[/tex]
We directly compute with the given concentration:
[tex]pOH=-log(6.5x10^{-12})\\\\pOH=11.2[/tex]
Moreover, fur such pOH, the pH will be:
[tex]pH=14-11.2=2.8[/tex]
Which means that such solution is an acid solution.
Best regards.
Answer:
11.2
Explanation:
Polyatomic ion formula for aluminum hydroxide
Answer:
Al(OH)3 ? i hope this is what you mean.
Answer:
The formula for aluminum hydroxide is Al(OH)3.
Explanation:
Typically, metal hydroxides form strong bases in solution. Aluminum hydroxide is special compound because it is amphoteric. This means it can react as a base or as an acid.
How are plastic containers different from paper containers? How are they the same?
Answer:
Paper is Not Reuseable like plastic.
Explanation:
please help! BRAINLIEST to right answerrrr
Answer: from the hotter surface to the colder one
Explanation:
Answer:d
d
Explanation:
Which shows an isomer of the molecule below?
Answer:
D
Explanation:
An isomer is a molecule with the same number of atoms as another compound, but they differ in arrangement of the atoms.
Answer:
D
Explanation:
A P E X
Sometimes in lab we collect the gas formed by a chemical reaction over water (see sketch at right). This makes it easy to isolate and measure the amount of gas produced.
Suppose the CO gas evolved by a certain chemical reaction taking place at 55 degree C is collected over water, using an apparatus something like that in the sketch, and the final volume of gas in the collection tube is measured to be 117 ml.
Calculate the mass of CO that is in the collection tube. Round your answer to 2 significant digits. You can make any normal and reasonable assumption about the reaction conditions and the nature of the gases.
Answer:
The correct answer is 0.12 grams.
Explanation:
The mass of carbon monoxide or CO collected in the tube can be determined by using the ideal gas equation, that is, PV = nRT.
Based on the given question, P or the pressure of the gas is given as 1 atm, volume of the gas collected in the tube is 117 ml or 0.117 L.
The number of moles or n can be determined by using the equation, mass/molar mass.
R is the universal gas constant, whose value is 0.0821 L atmK^-1mol^-1, and temperature is 55 degree C or 328 K (55+273).
On putting the values we get:
n = PV/RT
= (1 atm*0.117 L) / (0.0821 L atmK^-1mol^-1 * 328 K)
= 0.0043447 mol
Therefore, mass of CO will be moles * molar mass of CO
= 0.0043447 mol * 28 g/mol
= 0.12 g
How many grams of californium-254 will remain after 363 days if we
start with 64.0 grams of this substance? The half-life of californium-254
is 60.5 days.
Answer:
1.02 g OF CALIFORNIUM-254 WILL REMAIN AFTER 363 DAYS IF 64 g REACTS WITH HALF LIFE OF 60.5 DAYS.
Explanation:
Half life of a chemical reaction is the time required for a radioactive element to decay to half its original mass.
We will use the formula:
Nt = No (1/2)^t/t1/2 where;
Nt = quantity of substance remaining = unknown
No = original mass of the substance = 64 g
t = time elapsed = 363 days
t1/2 = half life of the substance = 60.5 days
Putting the values into the equation, we have:
Nt = 64 * (1/2)^(363/60.5)
Nt = 64 * (1/2) ^6
Nt = 64 * 0.015625
Nt = 1.0156
The amount of californium-254 remaining after 363 days is approximately 1.02 g
What is the pH of a 1.4 M pyridine solution that has Kb = 1.7 × 10-9? The equation for the dissociation of pyridine is C5H5N(aq) + H2O(l) ⇌ C5H5NH+(aq) + OH-(aq). What is the pH of a 1.4 M pyridine solution that has Kb = 1.7 × 10-9? The equation for the dissociation of pyridine is C5H5N(aq) + H2O(l) ⇌ C5H5NH+(aq) + OH-(aq). 4.31 9.69 8.72 10.69
Answer:
pH = 9.69
Explanation:
When pyridine (C₅H₅N) is added to water, the equilibrium that occurs is:
C₅H₅N(aq) + H₂O(l) ⇌ C₅H₅NH⁺(aq) + OH⁻(aq) Kb = 1.7x10⁻⁹
Where Kb is defined as:
Kb = 1.7x10⁻⁹ = [C₅H₅NH⁺] [OH⁻] / [C₅H₅N]
If you have a solution of 1.4M C₅H₅N, the equilibrium concentration of each specie is:
[C₅H₅N] = 1.4 - X
[C₅H₅NH⁺] = X
[OH⁻] = X
Where X represents the reaction coordinate
Replacing in Kb expression:
1.7x10⁻⁹ = [X] [X] / [1.4 - X]
2.38x10⁻⁹ - 1.7x10⁻⁹X = X²
0 = X² + 1.7x10⁻⁹X - 2.38x10⁻⁹
Solving for X:
X = -0.0000488M → False answer, there is no negative concentrations
X = 0.0000488M → Right answer
Thus, [OH⁻] = 0.0000488M. As pOH = -log [OH⁻]
pOH = 4.31
Knowing pH = 14 - pOH
pH = 9.69
The pH of a 1.4 M pyridine solution is 9.69. When pyridine (C₅H₅N) is added to water, the equilibrium occurs. The rate of forward reaction is equals to the rate of backward reaction.
Equilibrium for pyridine:When pyridine (C₅H₅N) is added to water, the equilibrium that occurs is:
C₅H₅N(aq) + H₂O(l) ⇌ C₅H₅NH⁺(aq) + OH⁻(aq) Kb = 1.7x10⁻⁹
Where Kb is defined as:
Kb = 1.7x10⁻⁹
Kb= [C₅H₅NH⁺] [OH⁻] / [C₅H₅N]
If you have a solution of 1.4M C₅H₅N, the equilibrium concentration of each specie is:
[C₅H₅N] = 1.4 - x
[C₅H₅NH⁺] = x
[OH⁻] = x
Where x represents the reaction coordinate
Replacing in Kb expression:
1.7*10⁻⁹ = [x] [x] / [1.4 -x]
2.38*10⁻⁹ - 1.7x10⁻⁹x = x²
0 = x² + 1.7*10⁻⁹x - 2.38*10⁻⁹
Solving for x:
x = 0.0000488M
Thus, [OH⁻] = 0.0000488M.
As pOH = -log [OH⁻]
pOH = 4.31
Knowing pH = 14 - pOH
pH = 9.69
Find more information about Equilibrium constant here:
brainly.com/question/12858312
which of the folowing alkanes can exhibit optical acitivity?(A)2-methylbutane,(B)2,3-Dimethylbutane,(C)3-methylpentane,(D)cyclobutane
Answer:
B
Explanation:
hope my answer helps you
Nitrogen gas was collected by water displacement. What was the pressure of the N2 collected if the temperature was 50 degrees celcius?
Answer:
Explanation:
Atmospheric pressure = 101.325 kPa
vapor pressure of water at 50°C = 12.332 kPa
pressure of N₂ = (Atmospheric pressure) - (vapor pressure of water at 50 oC)
pressure of N₂ = (101.325 kPa) - (12.332 kPa)
pressure of N₂ = 88.993 kPa
Therefore, the pressure of the N₂ collected if the temperature was 50 degrees celcius is 88.993 kPaHow do you calculate the number of protons, neutrons, and electrons in an element?
Answer:
The first thing you will need to do is find some information about your element. Go to the Periodic Table of Elements and click on your element. If it makes things easier, you can select your element from an alphabetical listing.
Number of Protons = Atomic Number
Number of Electrons = Number of Protons = Atomic Number
Number of Neutrons = Mass Number - Atomic Number
For krypton:
Number of Protons = Atomic Number = 36
Number of Electrons = Number of Protons = Atomic Number = 36
Number of Neutrons = Mass Number - Atomic Number = 84 - 36 = 48
Explanation:
hope this helps, have a good day :-)
Ascorbic acid (H2C6H6O6), also known as Vitamin C, is a polyprotic acid found in fruit, tomatoes, potatoes and leafy vegetables. The pKa's of the ascorbic acid are pKa1 = 4.10 and pKa2 = 11.80 at 25 °C. When ascorbic acid is titrated with NaOH and it takes 60.0 mL to remove all protons possible. In the titration curve, how many mL of NaOH are required to reach the first pKa? Another way of asking this is when presented with a titration curve of ascorbic acid where on the x-axis should one look (which volume of NaOH), if one wants to determine the first pKa?
Answer:
as when we add 60 ml it removes all the protons it means it is 2nd equivalence point of Ascorbic acid
and we know that pH = pKa1 when moles of NaOH is half of the 1st equivalence point
1st equivalence point = 2nd equivalence point / 2 = 60/2 =30ml
1st half equivalence point = 30/2 = 15ml
so when we add 15ml of NaOH
pH = pKa1 =15mL
CH³C⁴HCOCH³ how many atoms of each element are in one molecule of 2-heptanone
Answer:
- 7 carbon atoms.
- 14 hydrogen atoms.
- 1 oxygen atom.
Explanation:
Hello,
In this case, for the given compound, heptanone, whose chemical formula is:
[tex]CH_3COCH_2CH_2CH_2CH_2CH_3[/tex]
We can write the molecular formula showing the present atoms of each element:
[tex]C_7H_{14}O[/tex]
In such a way we have:
- 7 carbon atoms.
- 14 hydrogen atoms.
- 1 oxygen atom.
Best regards.
A 125 g sample of strontium was heated from 0°C to 20°C. It absorbed 750 J of energy. What is the specific heat capacity of iron?
Answer:
Specific heat capacity of iron (C) = 0.3 J/GK
Explanation:
Given:
Mass of sample (m) = 125 gram
Change in heat (ΔT) = 20°C - 0°C = 20°C
Absorbed energy (ΔE) = 750 J
Find:
Specific heat capacity of iron (C) = ?
Computation:
⇒ Specific heat capacity of iron (C) = ΔE / [mΔT]
⇒ Specific heat capacity of iron (C) = 750 / [125 × 20]
⇒ Specific heat capacity of iron (C) = 750 / [2,500]
⇒ Specific heat capacity of iron (C) = 0.3 J/GK
Answer:
Specific heat capacity of iron (C) [tex]= 0.3[/tex] J/g°C
Explanation:
As we know that
Specific heat capacity of iron (C) [tex]=\frac{\delta E}{ [m* \delta T]}[/tex]
Where [tex]\delta E[/tex] represents the change in the energy
m represents the mass of the sample and
[tex]\delta T[/tex] represents the change in temperature.
Given:
Mass of sample (m) [tex]= 125[/tex] gram
Change in heat ([tex]\delta T[/tex] ) [tex]20 - 0 = 20[/tex]
Absorbed energy ([tex]\delta E[/tex])[tex]= 750[/tex] J
Substituting the given values in above equation, we get -
Specific heat capacity of iron (C)
[tex]= \frac{750}{125*20}[/tex]
Specific heat capacity of iron (C) [tex]= 0.3[/tex] J/g°C
A student conducts an experiment to see how music affects plant growth. The student obtains four identical plants. Each one is potted in the same type of soil and receives the
same amount of sunlight and water each day. Plant A listens to classical music for three hours each day. Plant B listens to rock music for three hours each day. Plant C listens to
country music for three hours each day. Plant D does not listen to any music at all.
2. Based on the experiment in the scenario, which visual aid would be most helpful in showing the change in the plants' heights over time?
O A. A timeline
OB. A line graph
OC. A pie chart
D. A bar graph
Answer:
The type of music each plant listens to.
Explanation:
A variable is any factor or condition whose value is changing in an experiment. A variable can occur in different types or quantity, and three types of variable (independent, dependent, and controlled) can be found in an experiment. In the experiment described above, "the type of music each plant listens to" is the variable. It is an independent variable whose value is changing because it exists in different types and it is the one that the student is observing its effect on the plant’s growth. In this experiment, this variable which differ will also produce different results (or effects).
A certain element X has four isotopes. 5.845% of X has a mass of 53.93961 amu. 91.75% of X has a mass of 55.93494 amu. 2.123% of X has a mass of 56.93539 amu. 0.2820% of X has a mass of 57.93328 amu. What is the average atomic mass of element X? Express your answer numerically to four significant figures.
Answer:
Average atomic mass of element X is 56.19 amu
Explanation:
Given:
Four isotopes of X:
5.845% of X has a mass of 53.93961 amu.
91.75% of X has a mass of 55.93494 amu.
2.123% of X has a mass of 56.93539 amu.
0.2820% of X has a mass of 57.93328 amu.
To find: average atomic mass of element X
Solution:
Isotopes are variants of a particular chemical element such that they have the same number of protons but different number of neutrons.
Average atomic mass of element X = [tex]\frac{53.93961+55.93494+56.93539+57.93328}{4}=\frac{224.74322}{4}=56.185805\approx 56.19[/tex]
So, the average atomic mass of element X is 56.19 amu.
3Fe + 2O2 → Fe3O4 In this reaction, 200 grams of Fe react with 64 grams of O2. How many grams of Fe3O4 will be produced? A 230 grams B 264 grams C 280 grams D 460 grams
Answer:
just did it the answers b
Explanation:
If you start with 64g of a radioactive element how many half-lives would occur before 8g remain?
Answer:
3 half-lives
Explanation:
The half-life is the time that it takes to a radioactive element to decay to half of its initial amount.
Let's suppose we start with 64 g of the radioactive element.
After 1 half-life, the mass of the element will be 32 g.After 2 half-lives, the mass of the element will be 16 g.After 3 half-lives, the mass of the element will be 8 g.The image shows two different species. the image is a dog and a lizered
Which is a shared characteristic of these two species?
tail
scales
hair
body shape
Answer:
the tail
Explanation:
Answer:
A.) tails
Explanation:
Living large means we use a lot of energy. What are three ways people use energy in their daily lives?
Answer:
right now we are using energy by online learning on our laptops , air conditioning, and transportation
Explanation:
After 56.0 min, 40.0% of a compound has decomposed. What is the half‑life of this reaction assuming first‑order kinetics?
Answer:
Go ahead and plug in the percentages and time to find the answer.
Explanation:
The amount of a substance with half-life h, that remains after time t is 0.5t/h
Since 26% has decomposed, 74% remains.
So .74 = 0.580/h
ln .74 = (80/h) ln 0.5
h/80 = ln 0.5 / ln .74
h = 80 ln 0.5 / ln .74
h = 184.16 minutes
A compound A (C22H27NO) is insoluble in acid and base but reacts with concentrated aqueous HCl and heat to give a clear aqueous solution from which, on cooling, benzoic acid precipitates. When the supernatant solution is made basic, a liquid B separates. Compound B is achiral. Treatment of B with benzoyl chloride in pyridine gives back A. Evolution of gas is not observed when B is treated with an aqueous solution of NaNO2 and HCl. Treatment of B with excess CH3I, then aqueous Ag2O and heat, gives a compound C, C9H19N, plus styrene, C6H5–CH=CH2. Compound C, when treated with excess CH3I, then aqueous Ag2O and heat, gives a single alkene D that is identical to the compound obtained when cyclohexanone is treated with the ylid –:CH2– PPh3. Give the structure of A.
Answer:
See explaination
Explanation:
Please kindly check attachment for the step by step solution of the given problem
What parts of the body are tested for rigor Mortis
Which pigment is responsible for grey hair?
A
Eumelanin
В
Pheomelanin
с
Both Eumelanin and Pheomelanin
D
No pigment
3 of 10
Answer:
No pigment.
Explanation:
Pigment makes color, and hair loses color when it loses pigment.
The temperature of a 350. mL sample of gas increases from 27 °C to 227 °C. What is the final volume of the sample of gas, if the pressure and amount of gas in the container is kept constant?
Group of answer choices
Answer:
[tex]V_2=583.3mL[/tex]
Explanation:
Hello,
In this case, for the given constant amount and pressure of the, we apply the Charles' law which allows us to understand the volume-pressure behavior as a directly proportional relationship:
[tex]\frac{V_1}{T_1} =\frac{V_2}{T_2}[/tex]
Thus, since we need to compute the volume after the temperature increase (which must be expressed in absolute Kelvins), we obtain V2 as:
[tex]V_2=\frac{V_1T_2}{T_1} =\frac{350.0mL*(227+273.15)K}{(27+273.15)K}\\ \\V_2=583.3mL[/tex]
Best regards.
