Answer:
CrO
Explanation:
0.765g Cr
0.235g O
O = 16g/mol
Cr = 52g/mol
O 2-
Cr 2+, 3+, 6+
0.765 + 0.235 = 1
so 76.5% Cr
23.5% O
76.5/52 = 1.47/1.47 = 1
23.5/16 = 1.47/1.47 = 1
CrO
Iodine-131 has a half-life of 8 days. How long would it take for the number of unstable nuclei in the sample to be reduced from 1,000 to 125?
Answer:
After one-half life: 16 mg
After 2-half lives: 8 mg
After 3-half lives: 4 mg
After 4-half lives: 2 mg
After 5-half lives: 1 mg
(5 half-lives) x (8 days/half-life) = 40 days
or doing it the mathematical way: Let z be the number of days to be found:
1 mg = 32 mg x (1/2)^(z / 8 days)
1/32 = (1/2)^(z / 8 days)
log (1/32) = (z / 8 days) x log (1/2)
z / 8 days = log (1/32) / log (1/2)
z = 8 days x log (1/32) / log (1/2) = 40 days
Explanation:
Iodine-131 has a half-life of 8 days, then it would it take for the number of unstable nuclei in the sample to be reduced from 1,000 to 125 is 512 days.
How do we calculate total time?Total time of the reduction of any substance from an initial concentration to a particular concentration will be calculated as:
T = (t)ⁿ, where
n = number of half lives
t = half life time = 8 days
1st half life: 1000 → 500
2nd half life: 500 → 250
3rd half life: 250 → 125
So number of half life times is 3. On putting values we get,
T = (8)³
T = 512 days
Hence total duration of time is 512 days.
To know more about half life time, visit the below link:
https://brainly.com/question/25750315
PLEASE HELP ME ASAP! CHEMISTRY TUTOR
SEE ATTACHED
Answer:
[tex]\large \boxed{\text{-827.4 kJ}}[/tex]
Explanation:
We have three equations:
1. 2H₂S(g) + O₂(g) ⟶ 2S(s, rhombic) + 2H₂O(g) ; ∆H = -442.4 kJ
2. S(s, rhombic) + O₂(g) ⟶ SO₂(g); ∆H = -296.8 kJ
3. PbO(s) + H₂S(g) ⟶ PbS(s) + SO₂(g); ∆H = -104.3 kJ
From these, we must devise the target equation:
4. 2PbS(s) + 3O₂(g) ⟶2PbO(s) + 2SO₂(g); ΔH = ?
The target equation has PbS(s) on the left, so you reverse Equation 3 and double it.
When you reverse an equation, you reverse the sign of its ΔH.
When you double an equation, you double its ΔH.
5. 2PbS(s) + 2H₂O(g) ⟶ 2PbO(s) + 2H₂S(g); ∆H = 208.6 kJ
Equation 5 has 2H₂O on the left. That is not in the target equation.
You need an equation with 2H₂O on the right, so you copy Equation 1.
6. 2H₂S(g) + O₂(g) ⟶ 2S(s, rhombic) + 2H₂O(g) ; ∆H = -442.4 kJ
Equation 6 has 2S(s, rhombic) on the right. That is not in the target equation.
You need an equation with 2S(s, rhombic) on the left, so you double Equation 2.
7. 2S(s, rhombic) + 2O₂(g) ⟶ 2SO₂(g); ∆H = -593.6 kJ
Now, you add equations 5, 6, and 7, cancelling species that appear on opposite sides of the reaction arrows.
When you add equations, you add their ΔH values.
You get the target equation 4:
5. 2PbS(s) + 2H₂O(g) ⟶ 2PbO(s) + 2H₂S(g); ∆H = 208.6 kJ
6. 2H₂S(g) + O₂(g) ⟶ 2S(s) + 2H₂O(g) ; ∆H = -442.4 kJ
7. 2S(s) + 2O₂(g) ⟶ 2SO₂(g); ∆H = -593.6 kJ
4 . 2PbS(s) + 3O₂(g) ⟶ 2PbO(s) + 2SO₂(g); ΔH = -827.4 kJ
[tex]\Delta H \text{ for the reaction is $ \large \boxed{\textbf{-827.4 kJ}}$}[/tex]
Oxygen is an example of a(n)
A. heterogeneous mixture
B. compound
C. element
O
OD. homogenous mixture
Reset Selection
Answer:
C. element. oxygen is an element
Explanation:
oxygen is element #8
Which of the following atoms has the largest atomic radius? Provide an explanation
a Hydrogen
b. Sodium
C Lithium
d Rubidium
Answer:
Rubidium 265 pm
Explanation:
As can be seen in the figures below, the atomic radius increases from top to bottom in a group, and decreases from left to right across a period
Hydrogen 53 pm
Lithium 167 pm
Sodium 190 pm
A. Element
B. Compound
C homogenous mixture
D heterogenous mixture
Explain how you could use Avogadro's Law given the grams of a known compound and volume.
According to Avogadro's law, volume is directly proportional to number of moles which is in relation with the grams of a compound.
What is Avogadro's law?
Avogadro's law is a gas law which states that the total number of atoms or molecules has a direct proportion to the volume occupied by a gas at a constant temperature and pressure.
It is closely related to ideal gas equation as it links temperature, pressure, volume and the amount of substance.It is given as, V∝n,
The straight line graph of volume versus moles is a straight line passing through the origin which implies that zero moles of gas occupy zero volume.The law was proposed by Amedeo Avogadro in year 1811.
The law can be derived from the assumption of kinetic theory of gases considering their ideal behaviour.
Learn more about Avogadro's law,here:
https://brainly.com/question/4133756
#SPJ2
At a party, you see someone on the floor with grayish skin, having
trouble breathing. This could be a sign of:
AN ALCOHOL OVERDOSE
AN OPIOID OR DEPRESSANT OVERDOSE
A STIMULANT OVERDOSE
ALL OF THE ABOVE
A person having trouble breathing could be a sign of
d. All of the above(alcohol overdose, depressant overdose, or stimulant overdose)
Causes of trouble breathing:Most instances of windedness are because of heart or lung conditions. These organs are engaged with shipping oxygen to your tissues and removing carbon dioxide, and issues with both of these cycles influence your relaxation.
At a party, if a person feels trouble breathing then it can be due to an alcohol overdose, depressant overdose, or stimulant overdose.
Thus, option D is correct.
Find more information about Breathing here:
brainly.com/question/766725
A scuba tank contains air at 2975 psi and 25°C. The tank is left in a car in the
hot sun and the temperature increases to 44°C. What will be the pressure (psi)
in the tank?
Answer:
The new pressure is 3164.58 psi.
Explanation:
We have,
Initial pressure, [tex]P_1= 2975\ psi[/tex]
Initial temperature, [tex]T_1=25^{\circ}=298.15\ K[/tex]
The tank is left in a car in the hot sun and the temperature increases to 44°C, [tex]T_2=44^{\circ} =317.15\ K[/tex]
Let [tex]P_2[/tex] is the final pressure in the tank. Gay Lussac's law,
[tex]P\propto T\\\\\dfrac{P_1}{P_2}=\dfrac{T_1}{T_2}\\\\P_2=\dfrac{P_1T_2}{T_1}[/tex]
Plugging all the values,
[tex]P_2=\dfrac{2975\times 317.15}{298.15}\\\\P_2=3164.58\ psi[/tex]
So, the new pressure is 3164.58 psi.
You want to test the effect of water temperature on the rate of sugar
dissolution. Which of the following is an example of a controlled experiment
to test this?
A. The temperatures of five beakers of 250 mL of water are kept
constant, and 10 g of sugar is added to each beaker.
B. The temperatures of five beakers of 250 mL of water are varied,
and 10 g of sugar is added to each beaker.
C. The temperatures of five beakers of 250 mL of water are varied,
and 10 g of sugar is added to each beaker while three of the
beakers are stirred.
D. The temperatures of five beakers of 250 mL of water are varied,
and different amounts of sugar are added to each beaker.
Answer:B
Explanation:
You want different temperatures for each beaker but everything else the same
Write the name of each numbered part of the eye.
How does a salt bridge improve a battery
The role of the salt bridge is to assure the neutrality of both compartments.
Which state of matter is by high density and definite shape?
A. Solid
B. Liquid
C. Both Liquid and Solid
D. Gas
Answer:
Solid
Explanation:
Solid has a definite shape and its molecules have high density.
Hope this will help you.
A student decreases the temperature of a 417 cm³ balloon from 278 K to 231 K. Assuming constant pressure, what should the new volume of the balloon be?
376 cm³
417 cm³
462 cm³
924 cm³
Answer:
346.5 cm³ or 347cm³
Explanation:
v1/T1 = v2/T2
417/278 = v2/231
v2 = 346.5 cm³
Nonrenewable resources are ?
Answer:
limited resources
Explanation:
nonrenewable resources are those resources found inside the earth that are in a fixed amount. They are being used at a faster rate, and cannot be renewed. These resources include fossil fuels,natural gas, and coal.
// have a great day //
Pressure increases from Earth’s surface toward the center of Earth.
True Or False
Answer:
True
Explanation:
The center receives pressure which is what creates convection currents
PLEASEEEE HELP MEEE
For the reaction 2H2 + O2 → 2H2O, how many grams of water are produced from 26.0 mol of hydrogen?
2 Points
Which separation technique involves heating the components of a solution to
their boiling points?
A. Separation by distillation
B. Separation by density
C. Separation by chromatography
D. Separation by melting point
Answer:
D. Separation by melting point
Answer:
SEPARATE BY DESTILATION
Explanation: just did the test
A substance that is made up of more than one atom is called _____.
Answer:
It is called a compound.
Explanation:
What is the percent by mass in a solution with 10.0 grams of solute and 25.0 grams of solvent?
Answer:
Percent by mass of solute is (10/35) x 100 = 28.57%
Percent by mass of solvent is (25/35) x 100 = 71.43%
Explanation:
10.0 grams of solute
25.0 grams of solvent
Total Mass = 35 grams
percent by mass = (Mass A / Total Mass) x 100
Percent by mass of solute is (10/35) x 100 = 28.57%
Percent by mass of solvent is (25/35) x 100 = 71.43%
If two electrically charged objects repel one another, which statement must be true? One object has more electrons, and the other has more protons. Electrons will flow from one object to the other when they touch each other. The two objects have the same electric charge. The objects do not have strong electrical fields.
Answer:
The two objects have the same electric charge.
Explanation:
Electrically charged objects repel if they are both of the same charge, ie plus plus or minus minus.
The statement, that describes two electrically charged objects repel one another is "the two objects have the same electric charge."
What is an electric charge?The feature of subatomic particles that causes them to experience a force when put in an electric and magnetic field is known as electric charge.
When one or more items are electrically charged, electrostatic interactions are widespread. Two items with opposing charges will attract each other.
Unlike the attractive force between two items with opposite charges, two objects with like charges repel each other. In other words, a positively charged object will repel another positively charged object. This repelling force will separate the two items.
Hence the correct answer is the two objects have the same electric charge.
Learn to know more about electrical charge here
https://brainly.in/question/29137445
#SPJ2
A salt is made by adding an excess of an insoluble metal oxide to an acid.
How can the excess metal oxide be removed? *
D filtration
B crystallisation
A chromatography
C distillation
Answer:
Filtration
Explanation:
Filtration is used to separate solid substances from liquids or large molecules from small molecules. Since, Acid is a liquid and metal oxide is solid so Filtration can be used to separate these two.
What are the units of measurement for atomic radius?
Answer:
Units used to measure atomic radius:
Angstroms (Å): This the most common unit used. Equivalent to 1.0 x 10-10 meters.
Nanometer (nm): Equivalent to 1.0 x 10-9 meters.
Picometer (pm): Equivalent to 1.0 x 10-12 meters.
The table below shows two conclusions about atoms based on experiments by Rutherford and Thompson. Which of these statements best explains why Rutherford and Thompson visualized the atom differently? Atoms of different elements contain different particles. New experimental processes provide new scientific evidence. A single model of an atom cannot be agreed upon by all scientists. Scientists believe in proposing theories which contradict current theories.
Answer:
Scientists with varied experimental processes and interests perceive things differently.
Explanation:
Scientists believe in proposing theories which contradict current theories. So the correct option is D.
What are the atomic models?
Recently, the structure of atoms has been discovered. Before the ideal model of an atom was found, several others were proposed and abandoned.
Atomic Model of J.J. Thomson
In his hypothesis, Thomson compared the definition of an atom to that of a Christmas pudding.He claimed that atoms are made up of a positively charged sphere with embedded electrons.Additionally, he claimed that because the magnitudes of positive and negative charges are equal, an atom as a whole is electrically neutral.
Atomic Model of Rutherford
Rutherford experimented with α-particle scattering on a gold sheet.He noticed that the majority of the negative ions did not deflect when they travelled through the gold foil.Small angles were experienced by certain α-particles, whereas almost 180° was experienced by others.This experiment led Rutherford to the conclusion that an atom's nucleus, a positively charged spherical centre with a radius of 10-10 metres, contains almost all of the atom's mass (having a radius of 10–15 m).
Therefore the correct option is D.
Read more about atomic models, here
https://brainly.com/question/1566330
#SPJ2
If they are traveling at the same speed, which will have the most kinetic energy?
A. A 5-kilogram ball
B. A 25-kilogram ball
C. A 10-kilogram ball
D. A 1-kilogram ball
Answer: B. (A 25 kg ball)
Explanation:
Since [tex]KE = \frac{1}{2} mv^{2} \\[/tex], and velocity is the same for all four balls, the ball with the greatest mass will have the greatest kinetic energy (since mass and KE are directly related). Below shows these calculations:
A. m = 5
[tex]KE = \frac{1}{2} mv^{2} \\[/tex]
[tex]KE = \frac{1}{2} (5)v^{2} \\[/tex]
[tex]KE = 2.5v^{2} \\[/tex]
B. m = 25
[tex]KE = \frac{1}{2} mv^{2} \\[/tex]
[tex]KE = \frac{1}{2} (25)v^{2} \\[/tex]
[tex]KE = 12.5v^{2} \\[/tex]
C. m = 10
[tex]KE = \frac{1}{2} mv^{2} \\[/tex]
[tex]KE = \frac{1}{2} (10)v^{2} \\[/tex]
[tex]KE = 5v^{2} \\[/tex]
D. m = 1
[tex]KE = \frac{1}{2} mv^{2} \\[/tex]
[tex]KE = \frac{1}{2} (1)v^{2} \\[/tex]
[tex]KE = 0.5v^{2} \\[/tex]
physical science 6.06 part one
Answer:2 for 5, 6 for7
Explanation:
What one advantage of owning a solar car ?
Answer:
You have no fuel cost and has low cost Maintenance
Explanation:
Which of the following is true for the theoretical yield of a reaction? (1 point) a It is always calculated as a ratio. b It is the yield from the excess reactant. c It is the yield from the limiting reactant. d It is always twice the value of the actual yield.
Answer:
It is calcualted based ion the yield from the limiting reactant
Explanation:
How many hours will it take for only 1.5625 mg to remain
Answer:
36 hours
Explanation:
Notice that you are given the actual table of how the isotope reduces , and it shows that for each period of 6 hours the isotope decays to half of the initial number.
EVery 6 hours, the reduction in number of mg of the isotope goes down in half'
100 mg, then 50 mg, then 25 mg, then 12.5 mg, then 6.25 mg, then 3.125 mg and finally (reaching 1.5625 mg
That was 6 periods of 6 hours each, which totals: 6 time 6 hours = 36 hours
Plz answer quickly with explanations. .....
Answer:
It would be gas b. The gas you are talking about is carbon dioxide and for the reaction to work the gas needs to be bubbled through into the lime water.
Explanation:
The carbon dioxide reacts with lime water which is a solution of calcium hydroxide to form the white precipitate of calcium carbonate CaCO 3.
Calculate the theoretical yield for the amount of sodium carbonate produced as a result of this chemical reaction. Record your final answer in the above data table.
Calculate the percent yield using your theoretical yield and the amount of sodium carbonate that was actually recovered. Record your final answer in the above data table.
How did your calculated mass of sodium carbonate compare with the actual mass you obtained from the experiment? If the two masses are different, suggest reasons for the difference.
Predict the amount of water and carbon dioxide that was produced as a result of this reaction.
1.
Mass of crucible
5.26 g
2.
Mass of crucible & NaHCO3
8.27 g
3.
Mass of NaHCO3 (2-1)
3.01g
4.
Theoretical Yield of Na2CO3
(Use the amount calculated in #3 as your starting amount)
g
5.
Mass of crucible & Na2CO3
7.13 g
6.
Mass of Na2CO3 – Actual Yield (5-1)
1.87 g
7.
% Yield = actual yield x 100
theoretical yield
%
Answer:
98.6%
Explanation:
First we put down the equation representing the decomposition of sodium bicarbonate.
2NaHCO3(s) ----> Na2CO3(s) + H2O(l) + CO2(g)
We can see from the data provided that the mass of sodium bicarbonate reacted is 3.01 g.
The number of moles of sodium bicarbonate reacted= mass of sodium bicarbonate/ molar mass of sodium bicarbonate
Molar mass of sodium bicarbonate= 84.007 g/mol
Number of moles of sodium bicarbonate=3.01 g/ 84.007 g/mol
Number of moles of sodium bicarbonate= 0.0358 moles
From the balanced reaction equation,
2 moles of sodium bicarbonate yields 1 mole of sodium carbonate
Hence 0.0358 moles of sodium bicarbonate yields 0.0358/2 = 0.0179 moles of sodium carbonate
Theoretical yield of sodium carbonate = number of moles of sodium carbonate × molar mass of sodium carbonate
Molar mass of sodium carbonate= 105.9888 g/mol
Theoretical yield of sodium carbonate= 0.0179 moles × 105.9888 g/mol
Theoretical yield of sodium carbonate= 1.897 g
Actual yield of sodium carbonate= 1.87 g
%yield of sodium carbonate= 1.87/1.897 ×100
%yield of sodium carbonate= 98.6%
