Sodium-25 after 3 minutes : 1.0625 mg
Further explanationGeneral formulas used in decay:
[tex]\large{\boxed{\bold{N_t=N_0(\dfrac{1}{2})^{t/t\frac{1}{2} }}}[/tex]
T = duration of decay
t 1/2 = half-life
N₀ = the number of initial radioactive atoms
Nt = the number of radioactive atoms left after decaying during T time
No=8 mg
t1/2=60 s
T=3 min=180 s
[tex]\tt Nt=No\dfrac{1}{2}^{T/t1/2}\\\\Nt=8.5\dfrac{1}{2}^{180/60}\\\\Nt=8.5(\dfrac{1}{2})^3\\\\Nt=1.0625~mg[/tex]
What is the compound NH3
A 25.225 g sample of aqueous waste leaving a fertilizer manufacturer contains ammonia. The sample is diluted with 75.815 g of water. A 14.842 g aliquot of this solution is then titrated with 0.1068 M HCl . It required 29.99 mL of the HCl solution to reach the methyl red endpoint. Calculate the weight percent NH3 in the aqueous waste
Answer:
1.43 (w/w %)
Explanation:
HCl reacts with NH3 as follows:
HCl + NH3 → NH4+ + Cl-
1 mole of HCl reacts per mole of ammonia.
Mass of NH3 is obtained as follows:
Moles HCl:
0.02999L * (0.1068mol / L) = 3.203x10-3 moles HCl = Moles NH3
Mass NH3 in the aliquot:
3.203x10-3 moles NH3 * (17.031g / mol) = 0.0545g.
Mass of sample + water = 22.225g + 75.815g = 98.04g
Dilution factor: 98.04g / 14.842g = 6.6056
That means mass of NH3 in the sample is:
0.0545g * 6.6056 = 0.36g NH3
Weight percent is:
0.36g NH3 / 25.225g * 100
1.43 (w/w %)Based on what you have seen in this gizmo what is the best definition of the doppler effect?
Answer:
Based on what you have seen in the Doppler Effect Gizmo, what is the best definition of the Doppler effect? A change in the frequency of a wave caused by the motion of the source relative to the observer. The increase in volume of a sound as the source approaches an observer.
Explanation:
show is a pedigree chart. the chart shows that sally is carrier for red-green color blindness
Answer:
you cant post pictures on brainly answers.... can you?
Explanation:
a single covalent bond is made up of
Answer:
In chemistry, a single bond is a chemical bond between two atoms involving two valence electrons. That is, the atoms share one pair of electrons where the bond forms. Therefore, a single bond is a type of covalent bond.
Explanation:
(copied from Google)
Liquid 1 has a density of 2.0 g/ml, Liquid 2
has a density of 1.5 g/ml, and Liquid 3 has a density of 1.8 g/ml. Which liquidwill make up
the top layer?
Liquid 2 because the lower the density the more it floats and the higher the density the more it sinks. The order from top to bottom is liquid 2, liquid 3, liquid 1
Describe what a limiting reactant is
Answer:
The reactant in a chemical reaction that limits the amount of product that can be formed. The reaction will stop when all of the limiting reactant is consumed. Excess Reactant - The reactant in a chemical reaction that remains when a reaction stops when the limiting reactant is completely consumed.
Explanation:
q=m(delta)T Calculate the final temperature reached when 324 J of heat is added to a 22.5g iron bar initially at 20.0 degrees C. The specific heat capacity of iron is 0.45 J/g degrees C.
Answer:
T(final) = 52°C
Explanation:
1st, you need to correct your heat flow formula => q = mcΔT.
m = 22.5g
c = 0.45 j/g·°C
ΔT = T(final) - T(initial) = T(final) - 20°C
q = (22.5g)(0.45j/g·°C)((final) - 20°C) = 324j
=> T(final) = [324j/(22.5g)(0.45j/g·°C)] + 20°C = 52°C
What is the structure of amylopectin?
Answer:
Not sure if you just wanted the basic structure or full on structure.
Explanation:
Which is an advantage of using gymnosperms as decorative outdoor plants around homes and businesses?
Most of them do not grow very tall.
Most of them stay green all year.
All of them produce colorful flowers,
All of them have sharp needle-like leaves.
Answer:
i just took the test the correct answer is "most of them stay green all year"
Explanation:
Answer:
its B :)
Explanation:
cuz im mr beast
The ion formed by an atom of sulfur when it gains two electrons is called a:
Do not answer cation or anion
Answer:
sulfide ion
Explanation:
however, when non-metalic elements gain electrons to form anions the end of their name is change to "-ide".foe example, a flourin atom gains one electronto become a flouride ion(F`) and sulfur gains two electrons to become a sulfide ion(s^2)
How much heat is required to vaporize 15.8 g CH3OH(l) at its boiling point? (∆Hvap = 38.0 kJ/mol) a a. 2.41 kJ b 77.0 kJ c 18.8 kJ d 600. kJ
Answer:
be.77.0kj.
Explanation:
add moles then times
Considering the definition of enthalpy of vaporization, the correct answer is option c. the heat required to vaporize 15.8 g of CH₃OH at its boiling point is 18.8 kJ.
When a material changes phase from solid to liquid, or from liquid to gas, a certain amount of energy is involved in this phase change.
In case of phase change from liquid to gas, this amount of energy is known as enthalpy of vaporization (symbolized as ∆H vap), also known as (latent) heat of vaporization or heat of evaporation.
In other words, the enthalpy of vaporization is the amount of energy required to change a unit of mass (for example, moles or kg) of a substance from phase liquid to phase gas at constant temperature and pressure.
In this case, you know that enthalpy of vaporization is ∆Hvap = 38.0 kJ/mol.
On the other side, you want to vaporize 15.8 g of CH₃OH. Then, being the molar mass of the compound 32 g / mole (that is, the amount of mass contained in one mole), the number of moles to be vaporized is:
[tex]15.8 gramsx\frac{1 mol}{32 grams}= 0.49375 moles[/tex]
Then, the heat required to vaporize 0.49375 moles of CH₃OH at its boiling point is calculated taking into account the enthalpy of vaporization by:
0.49375 moles× 38.0 kJ/mol= 18.76 kJ ≅ 18.8 kJ
Finally, the correct answer is option c. the heat required to vaporize 15.8 g of CH₃OH at its boiling point is 18.8 kJ.
Learn more:
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6.At a pressure of 5.0 atmospheres, a sample of gas occupies 40 liters. What volume
will the same sample occupy at 1.0 atmosphere?
(a) 50 L
(b) 100 L
O (C) 80 L
(d) 200 L
Answer:
The answer is 200 LExplanation:
The new volume can be found by using the formula for Boyle's law which is
[tex]P_1V_1 = P_2V_2[/tex]
where
P1 is the initial pressure
P2 is the final pressure
V1 is the initial volume
V2 is the final volume
Since we are finding the new volume
[tex]V_2 = \frac{P_1V_1}{P_2} \\[/tex]
So we have
[tex]V_2 = \frac{5 \times 40}{1} \\ = 5 \times 40[/tex]
We have the final answer as
200 LHope this helps you
can you help me out pleas
Answer:a a atom
Explanation:
Answer:
a. carbon
b. atomic number
c. mass number
d. 6
e. 7
f. 8
pls mark as brainliest
Which pair of atoms are isotopes ?
Answer:
If two atoms have different numbers of protons, they are different elements. However, if two atoms have the same number of protons, but different numbers of neutrons we refer to them as isotopes. Two terms we use to identify nuclides (isotopes) are atomic number and mass number.
Explanation:
Your Welcome!
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, in below given ways we can identify isotopes.
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.
Differing elements exist when two atoms contain different numbers of protons. If two atoms contain the same amount of protons but differing numbers of neutrons, they are referred to be isotopes.
Therefore, in above given ways we can identify isotopes.
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Which fossil fuel is made when plants from swamps are covered, pressed, and heated for millions of years? A Coal B Petroleum C Natural Gas D Nuclear
Answer:
A: COAL
Explanation:
Coal was created hundreds of millions years ago. When prehistoric plant life died and sank to the bottom of the swamp and was covered by layers of sediment.
What type of particles move to create electicity?
electrons
protons
neutrons
the answer is electrons.....
Answer:
electrons
Explanation:
A student drew a diagram of the quantum model of an atom, as shown.
A small circle is shown. Six light gray spheres and six dark gray spheres are shown inside the circle. On the outer side of the circle is another circle of larger radius. This circle has two small circle on its boundary. Another circle of even greater radius is on the outside of the second circle. This outermost circle has four small circles on its boundary.
Which of the following explains if the student's diagram is correct or incorrect?
A - The diagram is incorrect because electrons follow an elliptical path instead of a circular path.
B - The diagram is incorrect because the exact location of the electrons cannot be determined.
C - The diagram is correct because protons and neutrons are concentrated at the center of the atom.
D - The diagram is correct because electrons are present in distinct energy levels around the nucleus.
The diagram is correct because electrons are present in distinct energy levels around the nucleus. Option D
What is the quantum model?Let nus just take a minute to be able to remind ourselves that when we look at the atom that there are several subatomic particles that can be shown to be able to make up the atom. We know that the electron is the particle that can be shown to be arranged in shells.
What we saw in the inner or the core of the atom is the nucleus and the six grey spheres that we can see there would have to do with the nucleus of the atom that is in the question.
As we now look up at the shells, we can see the electrons as they have been arranged into the respective shells were they can be found in the atom on the basis of the energy that they possess.
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a solution is made by dissolving 25g of nacl in 300g of water. What is the mass percentage
Answer:
0.83 bar
That is
23/300*100
=0.83 bar
Question 4 of 5
Most paints include a pigment (the color), a binder (the
glue), and a solvent. The binder makes the paint color stick
to the surface being painted.
Which part of the manufacturing process occurs when binders are added to a
paint mixture?
A. Separating
B. Forming
C. Finishing
D. Combining
SUE
Answer:
answer is d Combining
Explanation:
I did the test and got it correct
As a chemical change takes place when binders are added to a paint mixture combining part of the manufacturing process occurs.
What are chemical changes?Chemical changes are defined as changes which occur when a substance combines with another substance to form a new substance.Alternatively, when a substance breaks down or decomposes to give new substances it is also considered to be a chemical change.
There are several characteristics of chemical changes like change in color, change in state , change in odor and change in composition . During chemical change there is also formation of precipitate an insoluble mass of substance or even evolution of gases.
There are three types of chemical changes:
1) inorganic changes
2)organic changes
3) biochemical changes
During chemical changes atoms are rearranged and changes are accompanied by an energy change as new substances are formed.
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Which are the products in the equation CH3SH + 4O2 → CO2 + SO2 +2H2O? Check all that apply. CH3SH O2 CO2 SO2 H2O
To calculate the atoms of an element in a given molecule, we need to multiply stoichiometry by the number that is written on the foot of that element. Therefore, the products are carbon dioxide, sulfur dioxide and water.
What is Balanced equation?Balanced equation is the one in which the total number of atoms of a species on reactant side is equal to the total number of atoms on product side. The mass of the overall reaction should be conserved. There are so many types of chemical reaction reaction like combination reaction, displacement reaction.
The other characteristic of balanced equation is that physical state should be written with each compound or molecule on reactant and product side. Physical state should be written in brackets. s means solid, l means liquid, g means gas.
The balanced equation is
CH[tex]_3[/tex]SH + 4O[tex]_2[/tex] → CO[tex]_2[/tex] + SO[tex]_2[/tex] +2H[tex]_2[/tex]O
The products that are formed in the given reaction are carbon dioxide, sulfur dioxide and water.
Therefore, the products are carbon dioxide, sulfur dioxide and water.
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each substance in a solution mixture is visible to the naked eye? True or False
would you like to explore outer space? Why or why not? If you could travel to any part of the galaxy at lightning speed would like to see what is truly out in the universe would you do it? Why or why not?
Answer:
Yes!
Explanation:
I think It would be fun!, Going thought space going from planet to planet. once i get back to earth i can make a document about my time in space.
Just enough 0.500 M HCl is added to 30.0 mL of 2.5 M NH3 to reach the equivalence point. The Kb of NH3 = 1.8 X 10-5
Write the balanced equation for this reaction.
What volume of 0.500 M HCl solution was added?
What is the molarity of the salt produced from the neutralization reaction?
What is the pH of the solution at the equivalence point?
a.NH₃+HCl⇒NH₄Cl
b.volume HCl=150 ml
c. pH=4.82
Further explanationReaction
NH₃+HCl⇒NH₄Cl
The equivalence point⇒mol NH₃=HCl
Titration formula :
M₁V₁n₁=M₂V₂n₂(n=acid base valence, NH₃=HCl=1)
mol NH₃
[tex]\tt 2.5\times 30=75~mlmol[/tex]
mol HCl=75 mlmol
Volume HCl :[tex]\tt \dfrac{75}{0.5}=150~ml[/tex]
Volume total :
[tex]\tt 150+30=180~ml[/tex]
molarity of salt(NH₄Cl)mol NH₄Cl=mol NH₃=75 mlmol=0.075 mol
[tex]\tt M=\dfrac{0.075}{0.180}= 0.42[/tex]
pH of solutionDissociation of NH₄Cl at water to find [H₃O⁺]
[tex]\tt NH_4+H_2O\rightarrow NH_3+H_3O^+[/tex]
ICE at equilibrium :
0.41-x x x
Ka(Kw:Kb)= 10⁻¹⁴ : 1.8.10⁻⁵=5.6.10⁻¹⁰
[tex]\tt Ka=\dfrac{NH_3.H_3O}{NH_4}=\dfrac{x^2}{0.41}[/tex]
[H₃O⁺]=x :
[tex]\tt \sqrt{5.6.10^{-10}\times 0.41}=1.515.10^{-5}[/tex]
pH=-log[H₃O⁺]
[tex]\tt pH=5-log~1.515=4.82[/tex]
HElp me plzzzzz??????
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:
Zn + 2HCl —> ZnCl2 + H2
Thus, we can write out the atoms present in both the reactant and the product by doing a simple head count. The atoms present are listed below:
Element >>> Reactant >>> Product
Zn >>>>>>>> 1 >>>>>>>>>> 1
H >>>>>>>>> 2 >>>>>>>>> 2
Cl >>>>>>>>> 2 >>>>>>>>> 2
Identify the true statements about introns.a- they code for polypeptide proteinsb- they have a branch site located 20 to 50 nucleotides upstream of the 3' splice sitec- they end with the nucleotides AG at the 3' endd- they begin with the nucleotides GU at the 5' ende- they tend to be common in bacterial genes
Answer:
The answer is "Option b, c, and d".
Explanation:
In such a gene, Autosomes are also the sequence for code and transposable elements, not the series of encoding. Through the expression of genes, such fragments of its introns are split through protein complexes throughout the translation process. There has been no kenaf fiber in the genomes of prokaryotic cells.
23.1 G Of HCI (a Strong Acid) Is Added To Water To Make 1250 ML Of Solution.
Answer:
[H₃O⁺] = 0.0507 M
pH = 1.29
Explanation:
23.1 g of HCI (a strong acid) is added to water to make 1250 mL of solution. Calculate [H₃O⁺] and pH of the solution.
Step 1: Given data
Mass of HCl (solute): 23.1 gVolume of solution: 1250 mLStep 2: Calculate the concentration of HCl
We will use the following expression.
[HCl] = mass HCl / molar mass HCl × liters of solution
[HCl] = 2.31 g / 36.46 g/mol × 1.250 L
[HCl] = 0.0507 M
Step 3: Calculate the concentration of H₃O⁺
HCl is a strong acid according to the following equation.
HCl(aq) + H₂O(l) ⇒ H₃O⁺(aq) + Cl⁻(aq)
The molar ratio of HCl to H₃O⁺ is 1:1. Then, [H₃O⁺] = 0.0507 M.
Step 4: Calculate the pH of the solution
We will use the following expression.
pH = -log [H₃O⁺]
pH = -log 0.0507
pH = 1.29
28 mL of 0.10 M HCl is added to 60.0 mL of 0.10 M Sr(OH)2. Determine the concentration of OHin the resulting solution.
Answer:
Explanation:
Sr(OH)₂.+ 2HCl = SrCl₂ + 2H₂O
Moles of HCl in 28mL of .10 M HCl = .028 x .1 = .0028 moles .
Moles of Sr(OH)₂ in 60mL of .10 M Sr(OH)₂ = .060 x .1 = .0060 moles
2 moles of HCl reacts with 1 mole of Sr(OH)₂
.0028 moles of HCl reacts with .0014 mole of Sr(OH)₂
moles of Sr(OH)₂ remaining = .0060 - .0014 = .0046 moles .
Sr(OH)₂ = Sr⁺ + 2OH⁻
1 mole 2 mole
.0046 .0092
Total volume of solution = 88 mL .
88 mL of solution contains .0092 moles of OH⁻
concentration of OH⁻ = .0092 / .088
= .1045 M .
When Strontium hydroxide, Sr(OH)₂ will react with hydrochloric acid (HCl) then the reaction formed will be:
Sr(OH)₂+ 2 HCl ⇒ SrCl₂ + 2 H₂O
The concentration of OH in the resulting solution will be 0.1045 M.
This can be calculated by:
Molarity (HCl) = 0.10 MVolume (HCl) = 28 mLMolarity (Sr(OH)₂) = 0.10 M Volume (Sr(OH)₂) = 60.0 mL[tex]\text{Molarity} = \dfrac{\text{moles}}{\text{volume of the solution in litres}}[/tex]
Moles of HCl = 0.028 x 0.1 = 0.0028 moles
Moles of Sr(OH)₂ = 0.060 x 0.1 = 0.0060 moles
2 moles of hydrochloric acid will react with 1 mole of Sr(OH)₂So, 0.0028 moles of HCl will react with 0.0014 mole of Sr(OH)₂Remaining moles of Sr(OH)₂ = 0.0060 - 0.0014 = 0.0046 moles
Sr(OH)₂ ⇒ Sr⁺ + 2OH⁻
1 mole 2 mole
0.0046 0.0092
Total volume of solution = 88 mL
88 mL of solution contains 0.0092 moles of OH⁻
Hence, concentration of OH⁻ :
[tex]= \dfrac{0.0092 }{0.088}[/tex]
= 0.1045 M
Therefore, 0.1045 M will be the concentration of OH in the solution.
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Determine the acid dissociation constant for a 0.010 M nitrous acid (HNO2) solution that has a pH of 2.70. Nitrous acid is a weak monoprotic acid and the equilibrium equation of interest is:________
Answer:
HNO₂ ⇄ H⁺ + NO₂⁻
Ka = 4.0 × 10⁻⁴
Explanation:
Step 1: Given data
Concentration of nitrous acid (Ca): 0.010 MpH of the solution: 2.70Step 2: Write the acid dissociation reaction
Nitrous acid is a weak acid that dissociates according to the following expression.
HNO₂ ⇄ H⁺ + NO₂⁻
Step 3: Calculate the concentration of H⁺
We will use the definition of pH.
pH = -log [H⁺]
[H⁺] = antilog - pH = antilog -2.70 = 2.00 × 10⁻³ M
Step 4: Calculate the acid dissociation constant (Ka)
For a weak acid, we can calculate Ka using the following expression.
Ka = [H⁺]²/Ca
Ka = (2.00 × 10⁻³)²/0.010
Ka = 4.0 × 10⁻⁴