Answer:
0.0003125 g
Explanation:
Given data:
Half life of iodine-125 = 60 days
Mass of iodine pellet = 0.020 g
Mass of iodine remain after one year = ?
Solution:
one year = 365 days
Number of half lives = Time elapsed/ half life
Number of half lives = 365 days/ 60 days
Number of half lives = 6
At time zero = 0.020 g
At 1st half life = 0.020 g/2 = 0.01 g
At 2nd half life = 0.01 g / 2 = 0.005 g
At 3rd half life = 0.005 g/2 = 0.0025 g
At 4th half life = 0.0025 g / 2 = 0.00125 g
At 5tht half life = 0.00125 g / 2 = 0.000625 g
At 6th half life = 0.000625 g/ 2 = 0.0003125 g
3. What factor (s) affect the potential energy?
Answer:
The factors that affect an object's gravitational potential energy are its height relative to some reference point, its mass, and the strength of the gravitational field it is in.
Explanation:
please help!!!! chemistry question
Answer:
protons-50
Neutrons-75
protons are 50, neutrons are 75
An atom of calcium becomes a cation when it forms an ionic bond with two atoms of chlorine. What is the charge on the calcium ion?
A. 1+
B. 2+
C. 3+
D. 4+
Answer:
2+
Explanation:
I just did this question.
How many protons, electrons, and neutrons does an atom with atomic number 50 and mass number 125 contain? *
If the 50 kg object slows down to velocity of 1 m\s how much Kinect energy dose it have
I am giving brainlyest to whoever answers the question. I need help with the conclusion and table one.
conclusion questions:
Write a conclusion statement that addresses the following questions:
• Explain how you determined the polarity of all your compounds by first predicting the polarity of water, and then mixing different solutes and solvents to find the polarities of the other substances.
• Which of your polarity and solubility predictions were correct?
table questions are in the photo
Answer:
Alikes dissolve. Polar substances dissolve in polar solvents and nonpolar substances dissolve in nonpolar solvents. So how they reacted showed us whether or not they were polar or nonpolar. Such as water and vinegar. They are both polar molecules so they were polar.
Enzymes are potent catalysts because they: A. drive reactions to completion while other catalysts drive reactions to equilibrium. B. are very specific and can prevent the conversion of products back to substrates. C. are consumed in the reactions they catalyze. D. lower the activation energy for the reactions they catalyze. E. increase the equilibrium constants for the reactions they catalyze.
Enzymes are potent catalysts because they lower the activation energy for the reactions they catalyze (Option D).
What is a catalyst?A catalyst is any molecule capable of lowering the activation energy of a given chemical reaction, thereby making it possible in normal conditions.
Proteins called enzymes and specific types of RNA called ribozymes are well known due to their ability to bind substrates in a chemical reaction in order to generate one or more chemical products, which always require a certain amount of energy in order to carry out such chemical reactions.
Therefore, with this data, we can see that enzymes are biological catalysts capable of lowering the activation energy and thus carry out chemical reactions in normal cellular conditions such as for example, convert sugar glucose (i.e. a carbohydrate) into two molecules of pyruvate, which is a step of cellular respiration metabolic pathway.
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Petroleum ether followed by dichloromethane is used to separate fluorene and 9-fluorenone. Why would reversing the order in which these solvents are used be unwise
Answer:
9-fluorenone binds more strongly to the stationary phase.
Explanation:
9-fluorenone is more polar than fluorene because it possesses a carbonyl group. Recall that the stationary phase is alumina and alumina is a polar adsorbent. Alumina is a top choice for the separation of components that contain a weakly or moderately polar component. These polar components of the mixture are retained for a longer time and more selectively by the adsorbent.
The fluorene is eluted first with the Petroleum ether, this makes it easier to elute the 9-fluorenone with the dichloromethane. The 9-fluorenone will be slower because it is more strongly attracted to the alumina owing to its polar carbonyl group.
Fluorene moves faster because its' polarity is the same as Petroleum ether and also opposite of the alumina. If the order of solvents is reversed and dichloromethane is first used, the 9-fluorenone binds more strongly to the alumnina making it difficult to elute fluorene using Petroleum ether.
How many atom in 5 moles of nitrogen?
Answer:
To start, you need know that all a mole means is you have 6.022 x 1023 atoms of that type. So if I tell you I have a mole of nitrogen, then I have 6.022 x1023 nitrogen atoms. That ugly number is called Avogadro's Constant, NA
Explanation:
hy its isnt the correct answer but checkout the equation hope it help help
Compare the planets Mars and Saturn. Describe how their common characteristics are similar.
the planets Mars and Saturn
Answer: Mars and Saturn both have celestial body. Mars and Saturn both revolve around the sun in their own orbits. Mars is the second smallest in the solar system while Saturn is second largest in the solar system.
(Just to clarify and correct the other person who answered....they both do not have rings. Saturns does, but Mars does not.)
Explanation:
What creates gas pressure in a container such as a helium balloon?
A the vacuum maintained in the container
B atmospheric pressure acting on the outside walls of the container
C the simultaneous collisions of fast-moving particles with the container
D the attractive forces between gas particles inside the container
Answer:
C the simultaneous collisions of fast-moving particles with the container
Explanation:
Is the Statue of Liberty changing color from copper to teal a physical change?
Answer:
No its a chemical Change
Explanation:
Answer: chemical change
Explanation: Copper turns green because of chemical reactions with the elements. ... Just as iron that is left unprotected in open air will corrode and form a flaky orange-red outer layer, copper that is exposed to the elements undergoes a series of chemical reactions that give the shiny metal a pale green outer layer called a patina.
Which of these is an example of physical weathering?
A. Blowing away of lighter rock particles
B. Rock breaking up to due to mechanical force
C. Rock breaking up due to carbonic acid
D. Settling down of tick particles in a new location
Answer:
c
Explanation:
c
We dissolve 345 g of calcium acetate in enough water to make 1.2 L of solution. What is the osmotic pressure of this solution at 54 ∘C? Express your answer in atm.Î
Answer:
[tex]\Pi=146.3atm[/tex]
Explanation:
Hello.
In this case, since the osmotic pressure is computed via:
[tex]\Pi =i*c*RT[/tex]
Whereas the van't Hoff's factor of calcium acetate (molar mass = 158.17 g/mol) is 3 as it dissociates in one calcium ion and two acetate ions, the concentration is:
[tex]c=\frac{345g*\frac{1mol}{158.17g} }{1.2L}=1.82mol[/tex]
Therefore, the osmotic pressure is:
[tex]\Pi =3*1.82mol*0.082\frac{atm*L}{mol*K}*(54+273.15)K\\\\\Pi=146.3atm[/tex]
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Neutrons have a mass of __________ unit and a charge of __________.
Answer: 1 unit, charge of 0.
Explanation: Neutrons have a charge of 0 because they are neutral. Both protons and neutrons have a mass of 1 Amy.
3. Identities of the components in a mixture may be determined by a technique called spiking. Suppose you had run a gas chromatogram on your product and had then deliberately added a drop of a known sample of 3-methylcyclohexene to a drop of your product. What would you expect the new chromatogram to show you?
Answer:
Explanation:
Suppose we dehydrate 2-methylcyclohexanol, the products formed are 1-methylcyclohexene and 3 methylcyclohexene, where 1-methylcyclohexene tends to be the major product because it has the tendency of more substituted double bond.
In any event, gas chromatography method usually reveals two products with their relative amounts but not their identities.
Now, if we carry out a reaction containing those two products and let's say we have a peak 10:1. Then, we add a little drop of 3-methylcyclohexene to the mixture and carry out the test again.
Let's say that the new ratio is 3:1. Therefore, we can conclude that the minor product is 3-methylcyclohexene. However, if the ratio is larger, let say 20:1, then the original sample's major product is 3-methylcyclohexene.
We expect new chromatogram to show the major quantity of one of the formed products.
What is gas chromatography?Gas chromatography is a kind of analytical method in the chemistry to separate and analyze the components of any compound by the adsorption process.
When we already run our product on the gas chromatogram and after the result we add a drop of 3-methylcyclohexene in the product then we don't observe much difference in the result. Because from the gas chromatography result we only get the quantity of any substance not the identity. If already in the product 3-methylcyclohexene was present then in that condition we get a higher peak in graph and identify the component of product.
Hence, 3-methylcyclohexene gives idea about the quantity.
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What is the solution of the inequality shown
below?
a-3 > 5
Answer:
a>8
Explanation:
Hoped that helped!
Answer:
[tex]a > 8[/tex]
Explanation:
If we take a look at this problem, we can see that we need to solve for a.
[tex]a - 3 > 5[/tex]
Just like solving a normal equation, we can take add 3 on both sides like so:
[tex]a - 3 > 5\\ +3 +3\\----\\a > 8[/tex]
As our final answer, we get [tex]a[/tex] is greater than 8!
Hoped this helped!
-Bob Ross
this is a method used to separated parts of a mixture. large and small particles are separated using a screen
Answer:
Screening
Explanation:
Screening is usually done in large amounts.
Thanks!!
The combustion of liquid octane C8H18, in the presence of gaseous oxygent yields carbon dioxide and liquid water. In determining how many moles of water are produced by the reaction of 1.50 moles of octane, which conversion factor should be used?
Answer:
The answer to your question is given below.
Explanation:
We'll begin by writing the balanced equation for the reaction. This is illustrated below below:
2C8H18 + 25O2 —> 16CO2 + 18H2O
From the balanced equation above,
2 moles C8H18 reacted to produce 18 moles of H2O.
Finally, we shall determine the number of moles of H2O produced by the reaction of 1.5 moles of C8H18. This can be obtained as follow:
From the balanced equation above,
2 moles C8H18 reacted to produce 18 moles of H2O.
Therefore, 1.5 moles of C8H18 will react to produce = (1.5 × 18)/2 = 13.5 moles of H2O.
Thus, 13.5 moles of H2O were obtained from the reaction.
If a solution is 3% H2O2 by mass calculate its molarity. Assume the density is 1 g/mL. How does this molarity compare with the molarity of H2O2?
Answer:
0.882M of H2O2
Explanation:
A 3% solution by mass of H2O2 is a solution 3g of H2O2 in 100g of solution.
We need to convert the grams of solution to liters and the grams of H2O2 to moles to find molarity:
Moles H2O2:
3g H2O2 * (1mol / 34.01g) = 0.0882 moles H2O2.
Liters of solution:
100g solution * (1mL / 1g) * (1L / 1000mL) = 0.100L
Molarity (Ratio of moles of solute and liters of solution is:
0.0882 moles / L = 0.882M of H2O2
If 30.8 grams of hydrobromic acid react to form 0.4 grams of hydrogen, how many grams of bromine must simultaneously be formed
Answer:
30.4g of Br2
Explanation:
2HBr --> H2 + Br2
From the stochiometry of the reaction;
2 mol of HBr reacts to form 1 mol of Br2
Mass of HBr = Molar mass * Mol = 80.91 * 2 = 161.82g
Mass of Br2 = Molar mass * Mol = 159.8 * 1 = 159.8g
161.82g of HBr forms 159.8g of Br2
30. 8g would the form x?
161.82 = 159.8
30.8 = x
x = 30.8 * 159.8 / 161.82 = 30.4g of Br2
An atom has 11 protons, 12 neutrons, and 10 electrons. What is the charge?
Answer:
The atom is Na, sodium with a net charge of +1 because it lost an electron. it usually has 11 electrons.
Explanation:
sodium has a 11 protons with an atomic mass of 23-11=12 neutrons.
To see the number of atoms of an element in a given molecule we need to multiply stoichiometry to the number that is written on the foot of the element that is stoichiometry. Therefore, the charge on atom is +1.
What is atom?Atom is the smallest particle of any element, molecule or compound. Atom can not be further divided. Atoms contains nucleus in its center and electron that revolve around the atom in fixed orbit.
In the nucleus, proton and neutron are present. Electron has -1 charge while proton has +1 charge. Neutron is neutral that is it has no charge. So overall the charge of nucleus is due to only proton, not by neutron.
Since the number of electrons is 10. The number of protons is 11. So, there is loss of one electron, so the charge on atom is +1.
Therefore, the charge on atom is +1.
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How does de-icing roads with salt negatively impact the environment?
a. The road salt attracts deer that are then hit by motor vehicles.
b. It removes necessary salt from the local water courses.
C. The high salinity of the surface runoff is harmful to freshwater ecosystems.
d. The salt harbors salt eating bacteria that are toxic to animals
Answer:
c.
The high salinity of the surface runoff is harmful to freshwater ecosystems.
Explanation: cause that's the answer
The negative impact of deicing roads with salt on the environment is the high salinity of the surface runoff is harmful to freshwater ecosystems. Therefore, option (C) is correct.
What is deicing?Deicing can be described as the process of removing snow, ice, or frost from a surface. The application of chemicals that not only deice but also remain on a surface to delay the reformation of ice for a certain period of time.
Deicing is accomplished by mechanical methods through the application of heat, various salts or brines, alcohols, glycols, or by a combination of these different techniques.
Deicing of roads has been done with salt, often mixed with sand and gravel, on slick roads. Sodium chloride is generally used, as it is inexpensive and can be available in large quantities.
Since salt water still freezes at −18 °C and also has a tendency to cause corrosion, rusting the steel used in most vehicles. It can be toxic to some plants and animals depending on the concentration of salt.
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Vitamin C was measured by an electrochemical method in a 50.0-mL sample of lemon juice. A detector signal of 2.02 mA was observed. A standard addition of 1.00 mL of 29.4 mM vitamin C increased the signal to 3.79 mA. Find the concentration (in mM units) of vitamin C in the juice.
Answer:
The concentration (in mM units) of vitamin C in the juice is 0.64mM.
Explanation:
Let us calculate -:
Concentration of sample =>[tex]1ml\times 29.4mM[/tex]
= 29.4 mmol => 29.4mmol/50ml
= 0.588mM
plug in formula =>[tex]\frac{[final concentration]}{[v_1/v_2]} \times[final concentration]+[concentration of sample])[/tex] or
[tex]\frac{[x]}{[v_1/v-2]} \times[ x]+[concentration of sample])[/tex]
= [2.02 micro-Amber/3.79micro-Amber]
plug in and simplify
1.81x = 1.17
x = 0.64mM
Hence , the answer is 0.64mM.
8. When you know both the speed and direction of an object's motion, you know the
a. average speed of the object.
b. acceleration of the object.
c. distance the object has traveled.
d. velocity of the object.
Which event most likely occurs at point K?
cooling
cementing
melting
weathering
Answer:Melting
Explanation:
It was right when i took the test
A rock must be heated to between 600 and 1,300 degrees Celsius (1,100 and 2,400 degrees Fahrenheit) in order to melt and become molten rock. At point K the event occurring is melting.
The lithosphere of the Earth, also referred to as the crust, is a solid layer of the globe where rocks melt. Between 50 and 200 kilometers beneath the surface, rocks dissolve on average.
The rock will melt under excessive heat or pressure and turn into lava. Instead of metamorphic rock, an igneous rock will emerge as a result of this. An igneous rock called granite is created when magma cools slowly underneath.
Thus the correct option is C.
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What is the pH at the equivalence point of a weak acid, strong base titration if 25.0 mL of formic acid requires 29.80 mL of 0.1567 M NaOH. Ka for formic acid is 1.8 x 10-4.
Answer:
pH = 8.34
Explanation:
Formic acid reacts with a strong base producing formate ion, HCOO⁻, the equilibrium is:
Kb = [HCOOH] [OH⁻] / [HCOO⁻]
Where Kb is basic equilibrium constant = Kw / Ka = 1x10⁻¹⁴ / 1.8x10⁻⁴ = 5.56x10⁻¹¹
[HCOOH] and [OH⁻] comes both from formate ion, that means [OH⁻] = [HCOOH] = X, our incognite
And [HCOO⁻] is molarity of the solution. We need to determine this:
Moles of formate = Moles of NaOH added until equivalence point:
29.80mL = 0.02980L * (0.1567mol / L) = 4.670x10⁻³ moles NaOH = Moles Formate
And total volume of the solution is:
29.80mL + 25mL = 54.8mL = 0.0548L. Molarity is:
4.670x10⁻³ moles / 0.0548L = 0.08522M
Replacing in Kb expression:
Kb = [HCOOH] [OH⁻] / [HCOO⁻]
5.56x10⁻¹¹ = [X] [X] / [0.08522M]
4.738x10⁻¹² = X²
X = [OH⁻] = 2.177x10⁻⁶M
pOH = -log [OH⁻] = 5.66
And pH = 14 - pOH is:
pH = 8.34An ion formed from an atom has a 1- charge. The number of electrons present in the ion is 36 and the number of neutrons is 46. Identify the element by typing the name. For example: Hydrogen or Sodium.
Answer:
I believe the answer is Krypton.
Explanation:
I think it's krypton because usually, the number of electrons gives you the number of protons which can be used to find the atomic number.
Hope that helps!
what would a sunrise be like on Venus?
Answer:
But it is likley that sunsets and sunrises would be a lot slower due to Venus having a slow spin rate and the Sun being brighter due to Venus being closer to the Sun than Earth. Brightness: As noted above Venusian sunsets and sunrises would be a lot brighter and a lot more brilliant than on Earth due to Venus being closer to the Sun.
Explanation:
Calculate the concentration of vacancies in in fcc silver at 250oC given that the activation energyfor vacancy creation in silver is 79.5 kJ/mol. The units for your answer should be vacancies/cm3.
Answer:
The concentration of vacancies in fcc silver is [tex]6.6105\times 10^1^4 vacancies/cm^3[/tex]
Explanation:
Given is - silver (fcc lattice)
Temperature = 250°C = 523K
Activation energy for vacancy creation ,[tex]Q_v[/tex] =79.5 kJ/mol
Silver has a fcc crystal lattice structure with basis
Lattice parameter = 0.49nm = [tex]4.09\times 10^-^8[/tex]m
Now , let us calculate number of silver atoms"(lattice points)per [tex]cm^3[/tex]
[tex]N=\frac{4atoms/cell}{4.09\times10^-^8cm^3}[/tex]
=[tex]5.86\times10^2^2 Ag[/tex] atoms/[tex]cm^3[/tex]
Concentration of vacancies is given by the formula -
[tex]N_v =N_e_x_p\frac{-Q_V}{R.T_}[/tex]
here,
[tex]N_v = concentration of vacancies \\[/tex]
[tex]N= number of atoms[/tex] [tex]per[/tex] [tex]cm^3[/tex]
[tex]Q_v=[/tex] Activation energy for vacancy creation
T = Temperature
R = constant =[tex]8.314 J K^-^1 mole^-^1[/tex]
Now , putting the given values in the formula -
[tex]N_v= (5.85\times10^2^2atomscm^-^3)exp(\frac{-79.5KJ/mole}{8.314\timesJK^-^1mole^-^1})[/tex]
=[tex]6.6105\times10^1^4vacnacies/cm^3[/tex]
Hence , the answer is [tex]6.6105\times10^1^4vacnacies/cm^3[/tex]
