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.
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Most scientists recommend reducing carbon dioxide emissions. Less carbon dioxide in the atmosphere would be expected to?
Answer:
the air would be much cleaner and better for us to breath.
Explanation:
An element and an atom are different but related because
a) A particular element is made up of many different types of atoms b) A molecule is the same as an atom
c) An element is made up of all the same type of atom
d) An element is smaller than an atom
Answer:
c) An element is made up of all the same type of atom
Explanation:
Atoms are the smallest unit of an element that consists of protons, electrons and neutrons in its structure. An element is the smallest part of a chemical substance that cannot be disintegrated i.e. it cannot be broken down further.
Atoms and elements are different in many ways but they are connected in the sense that an element contains only one type of atoms. For example, aluminum element is made up of only aluminum atoms. Different atoms form a molecule but same atoms form an element.
The difference of the element and iron should be option c) An element is made up of all the same type of atom.
What are atoms and elements?The atom represents the smallest unit that comprises of protons, electrons, etc.
While on the other hand, the element represents the small part of the chemical substance that should not be disintegrated. Also, it cannot be split. They both should be interlinked.
Therefore, the option c is correct.
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Let's say you added too much magnesium in the amount of 0.1594 g. How much 8.00 M HCl (in mL) would be required to decompose the excess Mg present?
Mg(s) + 2 HCl(aq) --> MgCl2(aq) + H2(g)
Answer:
1.65×10^-3 L or 1.65 mL
Explanation:
Number of moles of magnesium in the excess reagent= mass of excess reagent/ molar mass of magnesium
Mass of excess magnesium= 0.1594 g
Molar mass of magnesium= 24 gmol-1
Number of moles of magnesium= 0.1594/24 = 6.6×10^-3 moles
From the reaction equation;
1 mole of magnesium reacted with 2 moles of HCl
6.6×10^-3 moles of magnesium will react with 6.6×10^-3 moles × 2= 13.2×10^-3 moles of HCl
But we know that;
Number of moles of HCl= concentration of HCl × volume of HCl
Volume of HCl= number of moles of HCl/ concentration of HCl
Since concentration of HCl= 8.00M
Volume of HCl= 13.2×10^-3/8.00= 1.65×10^-3 L or 1.65 mL
As much sugar as will dissolve is added to hot water. The water is then
cooled, and all of the sugar remains dissolved in the solution. Which term
describes the final sugar solution?
O A. Nonsaturated
O B. Saturated
C. Unsaturated
O D. Supersaturated
4. If 175 undecayed nuclei remain from a sample of 2800 nuclei, how many half-
lives have passed? (Show your work.) *
Your answer
Answer:
X = 4
Explanation:
Start 2800
End 175
175 = 2800x(0.5)^X
175/2800 = 0.5^X
0.0625 = 0.5^X
log(0.5 x) = log(0.0625)
x · log(0.5) = log(0.0625)
-0.301x = -1.204
x = -1.204/-0.301
x = 4
4. What is the name of A13+?
A)Aluminum ion
B)Aluminum
C)Aluminous ion
D)Aluminide ion
Answer:
Aluminum ion
Explanation:
I used Google tbh but it has a higher charge then a regular Aluminum atom
Find the molar mass of s6
Moles: 1
Weight, g : 192.3900
Answer:
Moles: 1
Weight, g : 192.3900
Explanation:
When we move from the bottom to the top of the periodic table:
Electronegativity increases and ionisation energy decreases
Both electronegativity and ionisation energy decreases
Both electronegativity and ionisation energy increases
They remain the same
Answer:
When we move from the bottom to the top of the periodic table:
Both electronegativity and ionisation energy increases.
Explanation:
The ionization energy I is the energy needed to start an electron to a gaseous atom, isolated and in a fundamental state. The electrons are attracted to the nucleus, so it is necessary to provide energy to start them. You should keep in mind that the electrons of the last layer are always lost, because they are the weakest attracted to the nucleus.
In a group, the ionization energy increases upwards because when passing from one element to the bottom, it contains one more layer of electrons. Therefore, the valence layer electrons, being further away from the nucleus, will be less attracted to it and it will cost less energy to pluck them.
On the other hand, electonegativity is defined as the ability of an element to attract electrons that link it to another element.
When descending within the same group, the atomic radius increases and the ionization energy decreases, indicating that the electrons are less attracted to the nucleus and therefore the electronegativity decreases from top to bottom.
A. Element
B. Compound
C homogenous mixture
D heterogenous mixture
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.
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What is amplitude in chemisty
Answer:
CHEMISTRY GLOSSARY
Amplitude is the displacement of a wave from zero. The maximum amplitude for a wave is the height of a peak or the depth of a trough, relative to the zero displacement line
Which phase lasts longer, a full moon or a new moon?
Select one: a. Full moon
b. New moon
C. They both last for the same number of days.
Answer: Definitely the answer is C. They both last for the same number of days.
Explanation: This requires the moon to complete a bit more than one orbit to be between the earth and the sun again. The period from new moon to full moon is one half a synodic month of 29.530/2 which is 14.765 days.
What are these labels?
Answer:
From left to right
Neutral
Acid
Base
Explanation:
So using HSAB theory hard and soft (Lewis) acids and bases.
OH - Is a Hard Base
H+ Strong Acid
A sample of octane undergoes combustion according to the equation 2 C8H18 + 25 O2 → 16 CO2 + 18 H2O ΔH°rxn = -11018 kJ. What mass of O2 (in grams) must react in order to generate 7280 kJ of energy?
Answer:
[tex]\large \boxed{\text{528.7 g} }[/tex]
Explanation:
It often helps to write the heat as if it were a reactant or a product in the thermochemical equation.
Then you can consider it to be 11018 "moles" of "kJ"
We will need a chemical equation with masses and molar masses, so, let's gather all the information in one place.
M_r: 32.00
2C₈H₁₈ + 25O₂ ⟶ 16CO₂ + 8H₂O + 11 018 kJ
n/mol: 7280
1. Moles of O₂
The molar ratio is 25 mol O₂:11 018 kJ
[tex]\text{Moles of O}_{2} = \text{7280 kJ} \times \dfrac{\text{25 mol O}_{2}}{\text{11 018 kJ}} = \text{16.52 mol O}_{2}[/tex]
2. Mass of O₂
[tex]\text{Mass of C$_{8}$H}_{18} = \text{16.52 mol O}_{2} \times \dfrac{\text{32.00 g O}_{2}}{\text{1 mol O}_{2}} = \textbf{528.6 g O}_{2}\\\text{The reaction requires $\large \boxed{\textbf{528.67 g O}_{2}}$}[/tex]
Where do you think trees get the nutrients they need to grow?
I
Which image shows a nonrenewable resource?
Answer: The orange can shall be your answer.
PLEASE HELP ME OUTTTT
How many grams of Fe3O4 are required to react completely with 54.29 grams of H2?
Fe3O4 + H2 → Fe + H2O
Answer:
Balance the equation
Fe3O4 + 4H2---> 3Fe +4H2O
Molar mass H2=(2*1)=2g/mol
Mass of H2=54.29grams
mole of H2= 54.29/2=27.15mol
4 mol of H2 = 1 mol Fe3O4
27.15mol of H2= 6.79mol of Fe3O4
Moles of Fe3O4 =6.79mol
Molar mass of Fe3O4= (56×3)+(16×4)
=168+64=232g/mol
Grams of Fe3O4 required to react with 54.29 grams of H2 is 232g/mol× 6.79mol
=1575.28g
is Naci a metal or none metel
Answer:
Salt (NaCl) is an ionic bond that consists of Sodium (Na) which is a metal with positive charge combines with Chlorine (Cl), a nonmetal with a negative charge.
Explanation:
What is the name of the body part that passes messages
from the sensory neurons to the brain?
o Lungs
O Nerve Cells
o Brain
o Stimulus please help me thanks
A compound contains 57.2 percent carbon, 6.1 percent hydrogen, 9.5 percent nitrogen, and 27.2 percent oxygen. What the empirical formula of the compound?
Answer:
So the empirical formula is C14H18N2O5
Explanation:
C = 57.2% = 12g/mol
H = 6.1% = 1g/mol
N = 9.5% = 14g/mol
O = 27.2% = 16g/mol
Empirical Formula for compound hmm
Assume
C = 57.2g
H = 6.1g
N = 9.5g
O = 27.2g
So we have
C = 57.2g/12g = 4.76 moles
H = 6.1g/1g = 6.10 moles
N = 9.5g/14g = 0.68 moles
O = 27.2g/16g = 1.70 moles
Divide each mole value by the smallest number of moles calculated. Round to the nearest whole number.
C = 4.76 moles / 0.68 moles = 7
H = 6.10 moles / 0.68 moles = 9
N = 0.68 moles / 0.68 moles = 1
O = 1.70 moles / 0.68 moles = 2.5
Ok so we now have the ratios but for O it's 2.5, have to be whole numbers so we will need to double all the numbers.
C = 14
H = 18
N = 2
O = 5
So the empirical formula is C14H18N2O5
what are the steps to go from the names of compounds to the formulas
Answer:
Explanation:
write down the formulas, use the expressions and formulas to convert
What volume of 10,0 M H2SO4 is required to prepare 4.0 L of 0.50 M H2SO4?
A) 0.20 L
B) 0.40 L
C) 0.50 L
D) 1.0L
E) 4.0L
Answer: A) 0.20 L
Explanation:
Molarity of a solution is defined as the number of moles of solute dissolved per Liter of the solution.
According to the neutralization law,
[tex]M_1V_1=M_2V_2[/tex]
where,
[tex]M_1[/tex] = molarity of stock [tex]H_2SO_4[/tex] solution = 10.0 M
[tex]V_1[/tex] = volume of stock [tex]H_2SO_4[/tex] solution = ?
[tex]M_2[/tex] = molarity of dilute [tex]H_2SO_4[/tex] solution = 0.50 M
[tex]V_2[/tex] = volume of dilute [tex]H_2SO_4[/tex] solution = 4.0 L
[tex]10.0\times V_1=0.50\times 4.0[/tex]
[tex]V_1=0.20L[/tex]
Therefore, the volume of 10.0 M [tex]H_2SO_4[/tex] solution needed to prepare 4.0 L of 0.50 M [tex]H_2SO_4[/tex] is 0.20 L
Which of the following changes depending on the strength of the gravity
field it is in?
A. None of these
B. Mass
C. Matter
D. Weight
Reset Selection
Answer:
D. Weight
Explanation:
Answer:
Weight
Explanation:
Answer via Educere/ Founder's Education
Label each element in the chemical reaction below with the correct oxidation state
NH3 (aq) + 3 HOCl (ax)
NCI () + 3 H20 (1)
Answer:
N = -3
H = +1
O = -2
Cl = +1
Explanation:
The balanced Equation of the reaction above is:
NH3 + 3HOCl ----> NCl3 + 3H2O
Where NH3 is ammonia;
HOCl is Oxochlorate (I) acid
NCl3 is nitrogen trichloride
H2O is water
Nitrogen in both Ammonia and Nitrogen trichloride has an oxidation state of -3. It shares three electrons with each of the three atoms of hydrogen and chlorine
Hydrogen in both Oxochlorate (I) acid and in water has an oxidation state of +1. Each atom shares an election with oxyen in both compounds.
Oxygen in both Oxochlorate (I) acid and water has an oxidation state of -2. Each atom shares two electrons with neighboring atoms; in HOCl, it shares with chlorine and hydrogen, while in H2O, it shares with two atoms of hydrogen.
Chlorine in both Oxochlorate (i) acid and Nitrogen trichloride has an oxidation state of +1. It shares an electron with each of it's neighboring bonded atoms.
Define Acid dissociation constant constant
Answer:
An acid dissociation constant, K a, (also known as acidity constant, or acid-ionization constant) is a quantitative measure of the strength of an acid in solution. It is the equilibrium constant for a chemical reaction ↽ − − ⇀ − + + known as dissociation in the context of acid–base reactions.
Explanation:
Can someone please show me how to solve this?
Answer:
4.38 Grams of C
Explanation:
How many grams of C are required to react with 52.6grams of Fe2O2?
Fe2O2 + C = 2Fe + CO2
Ratio 1:1
Fe2O2 = 144 Molar Mass
Fe2O2 52.6/144 = 0.365Moles of Fe2O2
Fe =56grams/mole = Charge 2+, 3+
O = 16grams/mole = Charge 2-
C = 12grams/mole = Charge 4+
So Ratio is 1:1 so we only need 0.365Moles of C so 4.38grams
An iron nail with a mass of 12 grams absorbs 12 Joules of heat. If the nail was initially at 25°C, what is the final temperature?
The conversation of cyclopropane to propene in the gas phase is a first order reaction with a rate constant of 6.7x10-⁴s-¹. a) if the initial concentration of cyclopropane was 0.25M , what is the concentration after 8.8min?b) how long (in min) will it take for the concentration of cyclopropane to decrease from 0.25M to 0.15M?
Answer: a) The concentration after 8.8min is 0.17 M
b) Time taken for the concentration of cyclopropane to decrease from 0.25M to 0.15M is 687 seconds.
Explanation:
Expression for rate law for first order kinetics is given by:
[tex]t=\frac{2.303}{k}\log\frac{a}{a-x}[/tex]
where,
k = rate constant
t = age of sample
a = let initial amount of the reactant
a - x = amount left after decay process
a) concentration after 8.8 min:
[tex]8.8\times 60s=\frac{2.303}{6.7\times 10^{-4}s^{-1}}\log\frac{0.25}{a-x}[/tex]
[tex]\log\frac{0.25}{a-x}=0.15[/tex]
[tex]\frac{0.25}{a-x}=1.41[/tex]
[tex](a-x)=0.17M[/tex]
b) for concentration to decrease from 0.25M to 0.15M
[tex]t=\frac{2.303}{6.7\times 10^{-4}s^{-1}}\log\frac{0.25}{0.15}\\\\t=\frac{2.303}{6.7\times 10^{-4}s^{-1}}\times 0.20[/tex]
[tex]t=687s[/tex]
Which of following is the most accurate description of a piston in an internal-
combustion engine?
A shaft that converts the up-and-down motion into a rotary motion
A plug that protrudes through the cylinder head and makes sparks that ignite the
air-and-fuel mixture
A can-shaped component that moves smoothly up and down and is the main
moving part
O A hollow metal tube drilled into the solid metal engine block
Answer:
A can-shaped component that moves smoothly up and down and is the main moving part
Explanation:
I chose the other answer that other person listed but got it wrong. This instead is the correct answer
Answer:
C. A can-shaped component that moves smoothly up and down and is the main
moving part
Explanation:
The piston is a can-shaped component that can move smoothly up and down inside the cylinder; it moves up to compress the air-and-fuel mixture and is pushed down when the spark plug ignites the mixture, which causes an explosion.
In a reaction, 25 grams of reactant
AB breaks down into 10 grams of
product A and an unknown amount
of product B. Using the law of conservation of mass, how much does product B weigh?
a. 25 g
B. 10 g
С. It cannot be determined from the given
information.
d
D. 15g
Answer:
D. 15g
Explanation:
The law of conservation of mass states that, in a chemical reaction, mass can neither be created nor destroyed. This means that the amount of matter in the elements of the reactants must be equal to the amount in the resulting products.
In this question, 25 grams of a reactant AB, was broken down in a reaction to produce 10 grams of products A and X grams of product B. According to the law of conservation of mass, the mass of the reactant must be equal to the total mass of the products. This means that 25 grams must also be the total mass of both products in this reaction. Hence, if product A is 10 grams, product B will be 25 grams - 10 grams = 15 grams.
Therefore, product B must be 15 grams in order to form a total of 25 grams when added to the mass of product A. This will equate the mass of the reactant AB and fulfill the law of conservation of mass.