Sodium-25 was to be used in an experiment, but it took 3.0 minutes to get the sodium from the reactor to the laboratory. If 8.0 mg of sodium-25 was removed from the reactor, how many mg of sodium-25 were placed in the reaction vessel 3.0 minutes later if the half life of sodium-25 is 60 seconds.
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]
Are bonds broken or formed, throughout each phase change present on a heating
curve?
HELP!!!!!!!!!!’nQuestion 3. Can you please explain how to get the answer? Starting with acetylene, devise a scheme to prepare 1-chloroheptanol
. There is more
than one way to complete this synthesis. It can be completed in as few as three reactions. You
can use any alkyl halides as needed as sources of carbon atoms.
Answer:
See explanation and image attached
Explanation:
Let us consider the mechanism attached to this answer. This is only one of the ways of synthesizing the required product.
The starting material is acetylene. This is reacted with sodamide in ammonia alongside methyl iodide. The process is repeated again, this time using butyl iodide. The alkyne is now reduced using hydrogen.
The alkane formed may now be chlorinated in the presence of light using the chlorine molecule. A mixture of alkyl halides are obtained.
Question 24 (3 points)
Choose the element below that has correct information about the number of energy
levels/orbitals: (Use a period table to answer this question).
Lithium (Li) has one energy level
Sodium (Na) has three energy levels
Potassium (K) has three energy levels
Fluorine (F) has seven energy levels.
Answer:
sodium
Explanation:
how does a squirrel get prepare for the winter months?
Answer:
Well, I have pet squirrels, and I know they get acorns and other food, and dig up certain spots on the ground, then put their food in there. And they have food for the winter.
The natural isotopes of Iron are Fe-55 and Fe-56. If the average atomic mass is 55.85, what are
the percent abundances of each isotope?
Answer:
15%
85%
Explanation:
Let the natural abundance of Fe-55 = y
the natural abundance of Fe - 56 = 1-y
Average atomic mass = 55.85
Unknown:
Percent abundances of each isotope = ?
Solution;
The average atomic mass of a substance is given as;
Average atomic mass = (mass x abundance)Fe - 55 + (mass x abundance)Fe - 56
Now insert the parameters and solve;
55.85 = (55 x y) + [56 x(1-y)]
55.85 = 55y + 56 - 56y
55.85 = -y + 56
55.85 - 56 = -y
-0.15 = -y
y = 0.15
1-y = 1 - 0.15 = 0.85
Percentage abundance;
Fe - 55 = 0.15 x 100 = 15%
Fe - 56 = 0.85 x 100 = 85%
Comprehensive studies have shown that forensic scientists should look for between 8 to 16 points to establish identification
based on fingerprints.
true or false
Answer:
FALSE
Explanation:
right answer on plato:)
A food item that is left out of the refrigerator turns brown and forms bubbles and gas. What are the signs that this is a chemical reaction?
Check all that apply.
Heat is produced.
Heat is absorbed.
Bubbles appear.
A precipitate forms.
The color changes.
Answer:
C & E
Explanation:
Compare and contrast how observations and results can be used to
support a conclusion to an experiment.
Answer:
by statistical analyses, especially by determining the p-value
Explanation:
In general, observations and results obtained from experimental procedures are subjected to a statistical test to check the robustness of the working hypothesis. The p-value is the most widely used statistical index in order to test such observations and results. The p-value is the statistical probability of obtaining extreme observed results when the null hypothesis is considered correct. A p-value lesser than 0.05 generally is considered statistically significant and then the null hypothesis can be rejected. In consequence, a very low p-value (which is obtained by statistical analysis of the observations and results), indicates that there is strong evidence in support of the alternative hypothesis.
Determine if any of the following reactions could be written as net ionic equations. Write yes or no in the blanks.
_____a. CH4 (g) + 2 O2 (g) = CO2 (g) + 2 H2 O(g)
_____b. Cu(s) + 2 AgNO3 (aq) = 2 Ag(s) + Cu(NO3 )2 (aq)
_____c. MgCl2 (aq) + 2 KOH(aq) = Mg(OH)2 (s) + 2 KCl(aq)
_____d. CaCO3 (s) + 2 HCl(aq) = CaCl2 (aq) + CO2 (g) + H2 O(l)
Reaction b,c and d could be written as net ionic equations.
Further explanationThe electrolyte in the solution produces ions.
The equation of a chemical reaction can be expressed in the equation of the ions
For strong electrolytes (the ionization rate = 1) is written in the form of separate ions, while the weak electrolyte (degree of ionization <1) is still written as an un-ionized molecule
In the ion equation, there is a spectator ions that is the ion which does not react because it is present before and after the reaction
When these ions are removed, the ionic equation is called the net ionic equation
For gases and solids including water (H₂O(l)) can be written as an ionized molecule
So only the dissolved compound is ionized ((expressed in symbol aq)
To see the reaction can be expressed in terms of the net ionic equation, we must see that there are two or more ions that are the same from both sides of the reactant and the product in the form of aquoeus (because the form of compounds in the form of gases, solids and liquids will remain molecular and non-ionized)
CH4 (g) + 2 O2 (g) = CO2 (g) + 2 H2 O(g)
No⇒no compounds in the aqueous form
Cu(s) + 2 AgNO3 (aq) = 2 Ag(s) + Cu(NO3 )2 (aq)
Cu(s) + 2 Ag⁺+ 2NO3⁻ (aq) = 2 Ag(s) + Cu²⁺ +2NO3⁻ (aq)
Cu(s) + 2 Ag⁺(aq) = 2 Ag(s) + Cu²⁺(aq)
yes, because there are NO3 (spectators ion) on both sides
MgCl2 (aq) + 2 KOH(aq) = Mg(OH)2 (s) + 2 KCl(aq)
Mg²⁺(aq)+2Cl⁻ (aq) + 2K⁺(aq)+2OH⁻(aq) = Mg(OH)2 (s)+ 2K⁺(aq)+2Cl⁻(aq)
Mg²⁺(aq)+2OH⁻(aq) = Mg(OH)2 (s)
yes, because there are 2Cl⁻ (aq) and 2K⁺(aq (spectators ion) on both sides
CaCO3 (s) + 2 HCl(aq) = CaCl2 (aq) + CO2 (g) + H2 O(l)
CaCO3 (s) + 2 H⁺(aq)+2Cl⁻(aq) = Ca²⁺(aq)+2Cl⁻ (aq) + CO2 (g) + H2 O(l)
CaCO3 (s) + 2 H⁺(aq) = Ca²⁺(aq) + CO2 (g) + H2 O(l)
yes, because there are Cl⁻ (spectators ion) on both sides
Which statement about the relationship between laws, hypotheses, and theories is true?
Describe the source of angle strain and torsional strain present in cyclopropane
Explanation:
The angle strain arises from the compression of the ideal tetrahedral bond angle of 109.5° to 60°. The large torsional strain occurs since all CH bonds on adjacent carbons are eclipsed.
The lateral angle that decrease in the lateral angle from 109.5 to 60 degree so, these is the main source of angle strain and torsional strain present in cyclopropane.
What is angle and torsional strain?Angle strain is the term for strain that results from departure from one or more ideal bond angles. Torsional strain is a chemical compound's resistance to bond twisting. Torsional strain between the bonds occurs when atoms separated by three bonds are arranged in an unstable staggered conformation rather than an eclipsed shape.
It exists in cyclopropane because its C-C-C bond angles must not exceed 60 degrees, which is less than the optimum bond angle of 109.5 degrees for tetrahedral carbon. It is the cause of these.
We are aware that three carbon atoms in a triangle plane break the cycle and cause each carbon to be sp3 hybridized. All carbon endeavors are sp3 hybridized, and we are aware that the sp3 hybrid angle is 109 degrees, 28 minutes at 109.5 degrees. But the single angle in cyclo-propane is only 60 degrees.
Personal strain results from the bending of bonds necessary to form a new molecule. The primary source of the angle strain and torsional strain found in cyclopropane is the decrease in lateral angle from 109.5 to 60 degrees.
Learn more about angle and torsional strain, Here:
https://brainly.com/question/21422023
#SPJ5
According to Boyle’s law, when the pressure of a gas increases at constant temperature, its volume
Answer:
the volume increases
Explanation:
Which statement best describes the relationship between the frequency and energy of light?
A) the lower the frequency the greater the energy of light. B) more information is needed since there is an additional term (h) in the equation relating frequency and energy. C) the higher the frequency the lower the energy of light. D) the higher the frequency the greater the energy of light.
Answer:
D) the higher the frequency the greater the energy of light.
Explanation:
Energy and frequency of light are directly connected. The higher the frequency ,the greater the energy of light.
As frequency increases, the energy of light also increases.
Frequency is the number of photons that passes through a point at a period of time. The more the the photons, the more energy light carries.Mathematically;
Energy = hf
h is planck's constant
f is the frequency.
Are bonds broken or formed, throughout each phase change present on a heating
curve?
Answer:
During a phase change no chemical bonds are broken. Atoms are not rearranged because a phase change is a physical change rather then a chemical change. However, intermolecular forces are almost entirely removed from the liquid since the intermolecular forces are what cause the liquid to be a liquid.
Explanation:the nature of the intermolecular forces (IMF) will not change when the state changes from solid to liquid, however, the number of IMF changes.
Which equation shows a physical change?
A.Pb(NO3)2 (aq) + 2KI(aq) → 2KNO3(aq) + PbI2(s)
B. HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l)
C.2H2O(l) → 2H2(g) + O2(g)
D.H2O(g) → H2O(s)
Answer:
The correct option is D
Explanation:
A physical change is a change in which no new substance is formed and can be easily reversible.
Of the options provided, option D is correct because gaseous water (steam) can be converted to solid water (ice) through freezing and can be reversed by heating up the solid water. Thus, this process does not involve the formation of any new substance.
Note that the processes of freezing and heating described must pass through the liquid phase.
If an object that stands 3 centimeters high is placed 12 centimeters in front of a plane mirror, how far from the mirror is the image located? Explain your reasoning.
Answer:
the mirror is 12 cm away from the image
Explanation:
; the image will be virtual and it will form at 12 cm distance behind the mirror.
help me please! asap please
Answer:
1. A2. C3. BExplanation:
i hope it helps ;)
A hydrogen filled balloon has a bolume of 8.3 L at 36 C and 751 torr. How many moles of hydrogen are inside the balloon?
Answer:
0.33 mol
Explanation:
Given data:
Volume of balloon = 8.3 L
Temperature = 36°C
Pressure = 751 torr
Number of moles of hydrogen = ?
Solution:
Temperature = 36°C (27 +273 = 300 K)
Pressure = 751 torr (751/760= 0.988 atm)
Formula:
The given problem will be solve by using general gas equation,
PV = nRT
P= Pressure
V = volume
n = number of moles
R = general gas constant = 0.0821 atm.L/ mol.K
T = temperature in kelvin
PV = nRT
0.988 atm × 8.3 L = n × 0.0821 atm.L/ mol.K × 300 K
8.2 atm.L = n × 24.63 atm.L/ mol
n = 8.2 atm.L / 24.63 atm.L/ mol
n = 0.33 mol
Is it true barium ion Games to electrons to make its valence shell full
Answer:
It is false
Explanation:
Barium does not gain electrons to make its valences shell full. In truth, Barium loses electrons to attain a complete octet configuration of its shell.
This is because, barium is electropositive and not electronegative.
As with most metals, barium will prefer to lose two electrons when forming bonds. The loss of two electrons makes it isoelectronic with the corresponding noble gas.In the combustion reaction 2C2H6 + 702 → 4C02 + 6H20, ethane gas reacts with oxygen to
produce carbon dioxide and steam. If 18.6 grams of C2H6 reacts with O2, how many moles of
steam does it produce?
Answer:
1.86moles
Explanation:
Given chemical reaction:
2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O
Mass of C₂H₆ = 18.6g
Unknown:
Number of moles of steam produced = ?
Solution:
2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O
We have checked and the equation is balanced.
Now, find the number of moles of C₂H₆ from the given mass;
Number of moles = [tex]\frac{mass}{molar mass}[/tex]
Molar mass of C₂H₆ = 2(12) + 6(1) = 30g/mol
Number of moles = [tex]\frac{18.6}{30}[/tex] = 0.62moles
From the balanced reaction equation:
2 mole of C₂H₆ will produce 6 moles of steam
0.62 moles of C₂H₆ will therefore produce [tex]\frac{0.62 x 6}{2}[/tex] = 1.86moles
Which of the following is a valid unit for specific heat?
Explanation:
The specific heat capacity is the amount of heat required to raise the temperature of 1mole or 1kg or 1g of substance by 1k or 1°C
This property is an intensive property of matter and does not depend on the quantity of matter present.
Some of the unit of specific heat are;
J/g°C, J/kg°C, J/mol°C, J/molK , Cal/g°C
a 500 kilogram sample of substance decays to 125 kilograms over a period of 21.53 years. what is the half life of the sample substance
Answer:
Half life = 10.765 year
Explanation:
Given data:
Mass of sample = 500 Kg
Mass left after 21.53 years = 125 kg
Half life of substance = ?
Solution:
At tome zero = 500 kg
At 1st half life = 500 kg/2 = 250 kg
At 2nd half life = 250 kg/2 = 125 g
Half life:
Half life = time elapsed / number of half life
Half life = 21.53 year/2
Half life = 10.765 year
need help please , thx
Answer:
vxxbvfdb
Explanation:
Answer:
sorry dude
Explanation:
i got no clue
Helpppp pleaseeeeeee
Answer: c
Explanation:
What did J.J. Thomson discover about electrons?
a
Atoms are indivisible.
b
Electrons are inside the nucleus of an atom.
c
Electrons are scattered in a positively charged atom.
d
Atoms of the same element have the same properties.
The answer is D
Brainliest?
What is the formula for Chromium (III) Bisulfite?
Answer:
Cr2(SO4)3
Explanation:
Match the terms with their definitions
Frequency, Amplitude, Crest, Wavelength, Medium, Trough
Matter distributed by energy
Highest point of transverse wave
Lowest point of transverse wave
Distance between midpoint of wave and crest
Distance traveled in one wave cycle
Number of waves that pass per second
(from brainpop waves.) PLease HeLP (Worth 25 POINTS)
Answer:
amplitude= distance between midpoint of a wave and crest
crest= highest point of transverse wave
wavelength= distance traveled in one wave cycle
medium= matter distributed by energy
trough=lowest point of transverse wave
frequency=number of waves that pass per second
Explanation:
A wave is a dynamic perturbation of one or even more quantities that propagates in a specific medium.
What is wave?A wave is a dynamic perturbation of one or even more quantities that propagates in physics, mathematics, or related sciences. When waves oscillate frequently around an equilibrium position at a certain frequency, they are said to be periodic. A traveling wave is one in which the whole waveform moves inside one direction; in contrast, a standing wave is one in which two periodic waves are overlaid and move in the opposing directions.
In a wave form, there are some points in which the wave amplitude seems reduced or even zero, and these positions have null vibration amplitudes. A wave equation or perhaps a one-way wave equation describing single wave propagation inside a specific direction is frequently used to describe waves.
amplitude= distance between midpoint of a wave and crest
crest= highest point of transverse wave
wavelength= distance traveled in one wave cycle
medium= matter distributed by energy
trough=lowest point of transverse wave
frequency=number of waves that pass per second
Therefore, a wave is a dynamic perturbation of one or even more quantities that propagates
To know more about wave, here:
https://brainly.com/question/13779567
#SPJ3
Balance chemical equation CuS(s)+HCl(aq)=CuCl2(aq)+ H2S(g)
Answer:
CuS(s) + 2HCl(aq) —> CuCl2(aq) + H2S(g)
Explanation:
CuS(s) + HCl(aq) —> CuCl2(aq) + H2S(g)
The above equation can be balance by by doing the following:
CuS(s) + HCl(aq) —> CuCl2(aq) + H2S(g)
There are 2 atoms of H on the right side and 1 atom on the left side. It can be balance by putting 2 in front of HCl as shown below:
CuS(s) + 2HCl(aq) —> CuCl2(aq) + H2S(g)
Now the equation is balanced since the number of atoms present in the elements are the same on both side of the equation i.e
Reactant:
Cu = 1
S = 1
H = 2
Cl = 2
Product:
Cu = 1
S = 1
H = 2
Cl = 2
Therefore, the balanced equation is:
CuS(s) + 2HCl(aq) —> CuCl2(aq) + H2S(g)
Which virus lastes the longest in the whole history? ( Sorry, I don't have options)
Answer:
COLD AND FLU!!!!
Explanation:
Answer:
CORONAVIRUS UGH
Explanation: