Answers
Bone age : 22,920 years
Further explanationGiven
Nt = 2.5 g C-14
No = 40 g
half-life = 5730 years
Required
time of decay
Solution
General 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
Input the value :
[tex]\tt 2.5=40.\dfrac{1}{2}^{t/5730}\\\\\dfrac{2.5}{40}=\dfrac{1}{2}^{t/5730}\\\\(\dfrac{1}{2})^4=\dfrac{1}{2}^{t/5730}\\\\4=t/5730\rightarrow t=22920~years[/tex]
Related Questions
Iontophoresis is a noninvasive process that transports drugs through the skin without needles. In the photo, the red electrode is positive and the black electrode is negative. The electric field between the electrodes will drive the negatively charged molecules of an anesthetic through the skin. Should the drug be placed at the red or the black electrode
Answers
Answer:
Follows are the explanation to this question:
Explanation:
When the drug is negatively charged, its negative electrolyte is annihilated to just the positive electrode. It is enticed, and it may not have a picture showing the electrode, however, We suppose that electrodes from either side of a skin slice. Its negative electrode will bypass or push thru the skin if in front of the counter terminal this becomes a red-positive electrode.
A sample of iron, which has a specific heat capacity of 0.449 Jg^-1℃^-1, is put into a calorimeter (see sketch at right) that contains 100.0 g of water. The iron sample starts off at container 93.3 °C and the temperature of the water starts off at 22.0 °C. When the temperature of the water stops changing it's 25.7 °C. The pressure remains constant at 1 atm.
Required:
Calculate the mass of the iron sample. Be sure your answer is rounded to 2 significant digits.
Answers
Answer:
[tex]m_{iron}=32.1g[/tex]
Explanation:
Hello!
In this case, since the interaction between hot iron and cold water allows the heat transfer from iron to water and therefore we can write up the following energetic equation:
[tex]Q_{iron}+Q_{water}=0[/tex]
Whereas the heat terms can be written in terms of mass, specific heat and temperature change:
[tex]m_{iron}C_{iron}(T_f-T_{iron}) + m_{water}C_{water}(T_f-T_{water}) = 0[/tex]
So we solve for the mass of iron as follows:
[tex]m_{iron} = \frac{m_{water}C_{water}(T_f-T_{water})}{C_{iron}(T_f-T_{iron}) }[/tex]
Now, we plug in the given data to obtain:
[tex]m_{iron} = \frac{-100g*0.449\frac{J}{g\°C} (25.7\°C-22.0\°C)}{0.449\frac{J}{g\°C} (25.7\°C-93.3\°C) }[/tex]
[tex]m_{iron}=32.1g[/tex]
Best regards!
PLEASE HELPPP!!! Calculate the mass (in grams) of lithium hydroxide that would be needed to produce 8.03 mol of
lithium sulfate in the reaction below.
2 LIOH + H2S04 -> Li2SO4 + 2 H20
Answers
Answer:
385g LiOH
Explanation:
Assuming the equation is balanced...
(8.03 mol Li2SO4) x (2 LiOH/ 1 Li2SO4)
= 16.1 mol LiOH ;
16.1 mol LiOH x (24g LiOH/ 1 mole LiOH) = 385g LiOH
The number of moles of LiOH needed to produce 8.03 moles is 16.06 moles. One mole of LiOH weighs, 23 g/mol. Hence, 16.06 moles weighs, 369.3 g.
What is lithium sulphate ?Lithium sulphate is an ionic compound formed by the donation of electron from the lithium metal to the sulphate group. It is formed by the reaction of lithium hydroxide with sulphuric acid.
As per the given balanced chemical equation of the reaction, the 2 moles of lithium hydroxide LiOH gives one mole of lithium sulphate. Then, number of moles of LiOH needed to give 8.03 mol of the product is:
2 × 8.03 = 16.06 mol.
Molar mass of LiOH = 23 g/mol.
mass of 16.06 moles of LiOH = 23 ×16.06 = 369.3 g.
Therefore, the required mass LiOH is 369.3 g.
Find more on LiOH:
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given mass of sodium sulphate contains 1.052 moles of oxygen atom then moles of sodium atom present in it would be equal to (ans=0.526)
how to solve this please help me...!
Answers
Ce clasă ești sa văd daca te pot ajuta
explain how the particles of a substance change as a substance changes from a solid to a liquid to a gas.
Answers
Answer:
Some substances can change from the solid state to the gas state without ever becoming a liquid. During this process, known as sublimation, the sur- face particles of the solid gain enough energy to become a gas.When dry ice becomes a gas, it absorbs thermal energy from water vapor in the air.
Explanation:
There diagrams imply that’s
A TISSUEs are always rectangular
B tissues are made up of cells
C Tissues all look the same
D tissues have the same Function
Answers
Answer:
b
Explanation:
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Fill in the coefficient needed to make the equation balanced.
1. _______ Na + Cl2 → ______NaCl
a. 2, 2
b. 2, 3
c. 2, 1
d. 2, 4
2. _______Al + _______S → Al2S3
a. 2, 2
b. 2, 3
c. 2, 4
d. 2, 6
3. ______ H2 + O2 → ______H2O
A. 2, 2
b. 2, 3
c. 2, 4
d. 2, 8
4. _______Fe + ______O2 → ______Fe2O3
a. 4, 2, 2
b. 4, 2, 1
c. 4, 3, 2
d. 4, 3, 1
Answers
Answer:
1 a
2 b
3 a
4. c
Explanation:
I need some help to determine the mole and grams pls I would really appreciate the help
Answers
Answer:
[tex]n_{FeS}=0.686molFeS \\\\n_{H_2S}=23.3gH_2S[/tex]
Explanation:
Hello!
In this case, according to the given chemical reaction, it is possible to apply the following stoichiometric setups in order to compute the moles of reacting FeS and the grams of produced H2S, given the mass of HCl (molar mass = 36.46 g/mol) as shown below:
[tex]n_{FeS}=50.0gHCl*\frac{1molHCl}{36.46gHCl}*\frac{1molFeS}{2molHCl}\\\\n_{FeS}=0.686molFeS \\\\\\m_{H_2S}=50.0gHCl*\frac{1molHCl}{36.46gHCl}*\frac{1molH_2S}{2molHCl}*\frac{34.04gH_2S}{1molH_2S} \\\\n_{H_2S}=23.3gH_2S[/tex]
Best regards!
A standard 10.00 g mass is weighed on an analytical balance 100 times. The average and standard deviation obtained gives 10.12 ± 0.03 g. A calibration service is called. After the balance is recalibrated, the new measurements show 10.00 ± 0.03 g. Did the recalibration result in improved accuracy or precision?
Answers
Answer:
There was an improvement in accuracy. There was no change in precision.
Explanation:
The average mass after recalibration is closer to the mass of the standard, so the recalibration improved the accuracy (the measurement is closer to an accepted 'true' value).
The standard deviation did not change, so the precision (or how disperse the measurements are) was not affected.
5.6 g of Iron reacts with excess fluorine gas.
The mass of iron fluoride produced is 11.3 g
What is the formula of the iron fluoride?
Answers
Answer: FeF3 Iron(III) fluoride
Explanation: 5.6 g = 1/10 mole Fe
11.3-5.6g F = 5.7 = 3/10 mole F
Indicate the electron pair geometry and the molecular geometry for each of the six compounds. Compound Electron pair geometry Molecular geometry CO 2 CO2 linear linear BF 3 BF3 SO 2 SO2 trigonal planar bent SiCl 4 SiCl4 tetrahedral tetrahedral PF 3 PF3 tetrahedral trigonal pyramidal OF 2 OF2 tetrahedral bent
Answers
Answer:
CO2
Electron pair geometry- Linear
Molecular geometry- Linear
BF3
Electron pair geometry - Trigonal planar
Molecular geometry- trigonal planar
SO2
Electron geometry - Trigonal planar
Molecular geometry - bent
SiCl4
Electron geometry- tetrahedral
Molecular geometry - tetrahedral
PF3
Electron pair geometry - tetrahedral
Molecular geometry- trigonal pyramidal
OF2
Electron pair geometry- tetrahedral
Molecular geometry- bent
Explanation:
Considering the molecule CO2, there are two regions of electron density in the molecule positioned at an angle of 180 degrees from each other hence the molecule is linear.
For BF3, the three bond pairs are arranged at the corners of a triangle to give a trigonal planar geometry at a bond angle of 120 degrees.
SO2 has two bonding groups and one lone pair giving three regions of electron density and a trigonal planar electron pair geometry. Due to the distortion to geometry caused by the presence of a lone pair, the molecule is bent.
For SiCl4, the four bonding groups are arranged at the corners of a regular tetrahedron hence it is tetrahedral both in electron pair geometry and in molecular geometry.
PF3 molecule has four regions of electron density corresponding to tetrahedral electron pair geometry. The presence of the lone pair leads to a trigonal pyramidal molecular geometry.
For OF2, there are four regions of electron density around the central oxygen atom. Two bond pairs and two lone pairs leads to a tetrahedral electron pair geometry but a bent molecular geometry is observed due to the two lone pairs.
A chemist carefully measures the amount of heat needed to raise the temperature of a 894.0g sample of a pure substance from to −5.8°C to 17.5°C. The experiment shows that 4.90kJ of heat are needed. What can the chemist report for the specific heat capacity of the substance?
Answers
Answer:
C = 0.2349 J/ (g °C)
Explanation:
Mass, m = 894.0g
Initial Temperature = −5.8°C
Final Temperature = 17.5°C
Temperature change = 17.5°C - (−5.8°C) = 23.3
Heat, H = 4.90kJ = 4900 J
Specific heat capacit, C = ?
The relationship between these quantities is given by the equation;
H = mCΔT
C = H / mΔT
C = 4900 / (894)(23.3)
C = 0.2349 J/ (g °C)
Why are acids called proton donors?
Answers
The relationship between acids and bases is more aggressive than the donor/acceptor terminology implies. Bases don't passively "accept" protons; they rip hydrogen ions from acids. Acids don't "donate" hydrogen ions; they surrender them.
Which example is a long-term environmental change?
O La Niña
O EI Nino
O climate change
O small asteroid impact
C
Answers
please help. it’s my last question.
Answers
Given
Atomic symbol
Required
Atomic composition
Solution
Atomic number = number of protons = number of electrons
Mass Number (A) is the sum of protons and neutrons
Number of protons and Number of Neutrons in nucleus
Number of electrons in the shell
From the picture:
protons = 3
neutrons = 4
electrons = 3
atomic number = protons = electrons = 3
mass number = protons + neutrons = 3+4 = 7
12) How many moles of CO can be produced from
10.0 mol of CO2
Answers
Answer:
5
Explanation:
There are 2 moles of CO in each CO2. 10 ÷ 2 = 5
A student is building a model of the layers of the Earth. Which material would best represent the crust?
a:grouping of magnetic balls
b:Styrofoam packing pellets
C:Bag of shredded paper
d:Thin layer of plaster
Answers
Answer:
d
Explanation:
The material that represents the crust is option d. Thin layer of plaster.
What is the crust and which material should be considered for it?It is the outermost shell of a planet i.e. terrestrial. The crust of the earth should be split into older, thicker continental crust, etc. Also, it is made of solid rocks and minerals. Due to this, the thin plaster layer represents the material for the crust.
Learn more about the earth here: https://brainly.com/question/17365118
WORTH 20 POINTS! MY LIFE DEPENDS ON IT HELP
Why do atoms share electrons in covalent bonds?
1. to become ions and attract each other
2. to fill their valence shell
3. to become more polar
4. to increase their atomic numbers
Answers
Answer:
2
Explanation:
Covalent bonding occurs when pairs of electrons are shared by atoms. Atoms will covalently bond with other atoms in order to gain more stability, which is gained by forming a full electron shell. By sharing their outer most (valence) electrons, atoms can fill up their outer electron shell and gain stability.
Answer:
To fill their valance shell and become stable!
Explanation:
Density of water calculation using a 10 mL graduated cylinder
10 mL graduated cylinder + 10 mL unknown liquid (g) 10 mL graduated cylinder (g) Volume of liquid (mL) Density (g/mL)
Trial 1 19.731 9.861 10.0
Trial 2 19.831 9.861 10.0
Trial 3 19.831 9.861 10.0
Trial 4 19.771 9.861 10.0
Trial 5 19.751 9.861 10.0
Required:
Calculate the average density for the gradudated cylinder measurements.
Answers
Answer:
Average density of the liquid = 0.992 g/mL
Explanation:
Density = mass/volume
mass of liquid = (mass of liquid + mass of cylinder) - mass of cylinder
Trial 1: mass of liquid = 19.731 - 9.861 = 9.87
volume of liquid = 10 mL
density of liquid = 9.87 g / 10 mL = 0.987 g/mL
Trial 2: mass of liquid = 19.831 - 9.861 = 9.97
volume of liquid = 10 mL
density of liquid = 9.97 g / 10 mL = 0.997 g/mL
Trial 3: mass of liquid = 19.831 - 9.861 = 9.97
volume of liquid = 10 mL
density of liquid = 9.97 g / 10 mL = 0.997 g/mL
Trial 4: mass of liquid = 19.771 - 9.861 = 9.91
volume of liquid = 10 mL
density of liquid = 9.91 g / 10 mL = 0.991 g/mL
Trial 5: mass of liquid = 19.751 - 9.861 = 9.89
volume of liquid = 10 mL
density of liquid = 9.89 g / 10 mL = 0.989 g/mL
Average density = (0.987 + 0.997 + 0.997 + 0.991 + 0.989)/5 = 4.961/5
Average density of the liquid = 0.992 g/mL
Can someone explain how it is 1?
Answers
Explanation:
You have 112 g of Fe.
The atomic mass of Fe is 56 g/mol
112g Fe/ 56g/mol = 2 mol Fe <---- you have to convert to moles of iron(iii) sulfate
From the balanced equation, you get that 2 moles of Fe react to produce 1 mole of Fe2(SO4)3
So, to convert:
2 mol Fe* (1 mol Fe2(SO4)3 / 2 mol Fe) = 1 mol Fe2(SO4)3
moles of Fe cancel and the answer is 1 mole of iron(iii) sulfate.
This is to be removed in brown sugar and to be rolled with a rolling pin?
Answers
Answer:
The lumps should be removed in brown sugar and to be rolled with rolling pin.
Explanation:
In preparing brown sugar as ingredients in baking and pastry, it is important to check if the sugar is lumpy. Although it is not the main ingredient in baking, it is important to check because it could affect the texture of the mixtures. Brown sugar is also much nutritious to white sugar that is why it is more commonly use. The brown sugar become lumpy because when brown sugar is exposed to air it gets harder because the molasses that keeps its soft evaporates that makes the sugar stick together. The rolling pin helps the lump to break up.
Breathing equipment used by rescue workers needs to capture the CO2 the humans breath out and produce O2 for them to breath in, like a plant during photosynthesis. One compound capable of doing this is potassium superoxide (KO2), which produces the salt by-product potassium carbonate. What is the balanced chemical equation for this reaction? Don't include states of matter.
Answers
Answer: [tex]4KO_2+2CO_2\rightarrow 2K_2CO_3+3O_2[/tex]
Explanation:
According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.
The balanced chemical equation for reaction of potassium superoxide with carbon dioxide to produce oxygen and potassium carbonate will be:
[tex]4KO_2+2CO_2\rightarrow 2K_2CO_3+3O_2[/tex]
Lithium diorganocopper (Gilman) reagents are prepared by treatment of an organolithium compound with copper(I) iodide. Decide what lithium diorganocopper (Gilman) reagent is needed to convert 1-bromopropane into propylcyclohexane. Draw the structure of the organolithium compound that is used to prepare Gilman.
Answers
Answer:
See explanation and image attached
Explanation:
The Gilman reagent is a lithium and copper (diorganocopper) reagent with a general formula R2CuLi. R is an alkyl or aryl group.
They are useful in the synthesis of alkanes because they react with organic halides to replace the halide group with an R group.
In this particular instance, we intend to synthesize propylcyclohexane. The structure of the lithium diorganocopper (Gilman) reagent required is shown in the image attached to this answer.
Police investigating the scene of a sexual assault recover a large blanket that they believe may contain useful physical evidence. They take it to the laboratory of forensic serologist Scott Alden, asking him to test it for the presence of semen. Noticing faint pink stains on the blanket, Scott asks the investigating detective if he is aware of anything that might recently have been spilled on the blanket. The detective reports that an overturned bowl of grapes and watermelon was found at the scene, as well as a broken glass that had contained wine. After the detective departs, Scott chooses and administers what he considers the best test for analysing the piece of evidence in his possession. Three minutes after completion of the test, the blanket shows a positive reaction. What test did Scott choose, and what was his conclusion? Explain your answer.
Answers
Answer:
Acid Phosphatase (AP) Test
Explanation:
Acid phosphate is an enzyme that is found in the body. It is secreted majorly by the prostrate gland into the seminal fluid. The acid phosphatase test is used to test for the presence of semen in items.
Scott chose the acid phosphatase test because it is very useful in testing for semen on large items such as blankets. The reaction time for an acid phosphatase test for semen is less than 30 seconds. Seeing that the test was completed in three minutes, Scott concluded that the positive reaction was as a result of some other fluid.
The detectives reported that an overturned bowl of grapes and watermelon was found at the scene as well as a broken glass that had contained wine. Scott knew that some fruit juices like that of watermelon give a positive reaction to the acid phosphatase test but with more time that of the semen fluid because the reaction is a very slow one.
Scott concluded that there was no presence of semen on the blanket and therefore there was no sexual assault.
Pls help!!!!!! In your own words, explain how chemists properly represent the law of conservation of matter in their chemical
equations.
Answers
Answer:
They represent it by ensuring that the number of atoms of each element (matter) in the reactant side is the same as the product side
Explanation:
The law of conservation of matter stated that matter can neither be created nor destroyed. Chemical equations involve combining atoms of elements. The compounds combined by chemists are called REACTANTS while the produced compounds are called PRODUCTS.
In order to conform to the law of conservation of matter, the same quantity of matter present in the reactants must be present in the products. This means that the number of atoms of each element (matter) in the reactant side must be the same as the product side. For example;
C6H12O6 + 6O2 → 6CO2 + 6H2O
In this chemical equation for photosynthesis, number of atoms in the reactant side (6 carbon, 12 hydrogen, 18 oxygen) are the same as that in the product side (6 carbon, 12 hydrogen, 18 oxygen), hence, this obeys the law of conservation of mass.
In a nutshell, chemists chemists properly represent the law of conservation of matter in their chemical equations by making sure that same number of atoms of reactants is present in the products.
Part A
Summarize your research, and describe the attributes of the savanna.
Answers
Answer:
Savanna regions have two distinct seasons - a wet season and a dry season. There is very little rain in the dry season. In the wet season vegetation grows, including lush green grasses and wooded areas.
Savannas are grasslands found in Africa, Australia, South America, and India. The climate is warm or hot. Savannas experience both dry and rainy seasons. Each year, savannas receive about 20 to 50 inches of rain in a span of six to eight months. The other months are dryer. There’s also a threat of wildfires because of the severe dryness during these months. Grasslands are true to their name because their vegetation is mostly grass. Savannas are home to a wide range of animals, including different species of beetles and insects, which many creatures consume. Squirrels, mice, elephants, gazelles, and antelopes are the plant-eating animals that live in the savanna. Hyenas, lions, and leopards are some of the meat-eating animals in these areas. Some of the nonliving components of the system include very porous soil that allows water to drain easily.
how many moles are in a 25.0 grams of carbon dioxide
Answers
answer:44.0095
Explanation:
sana makatulong
Answer:
44.0095
Explanation:
We assume you are converting between grams CO2 and mole. You can view more details on each measurement unit: molecular weight of CO2 or mol This compound is also known as Carbon Dioxide. The SI base unit for amount of substance is the mole.
Did i answer these right??
Answers
(ILL GIVE BREAINLIEST!! ) Which process(es) has steps called prophase, metaphase, anaphase, and telophase?
meiosis and mitosis
mitosis and fertilization
fertilization only
meiosis only
Answers
Answer:
mitosis and fertilization is a required answer.
Answer:
meiosis and mitosis
Explanation:
the difference is that meiosis goes through it twice.
Explain the order of dielectric constants for the following pairs of liquids. a) Carbon tetrachloride (2.2), chloroform (4.8) b) Ethanol (24.3) and methanol (32.6) c) Acetone (20.7) and formamide (110.0)
Answers
Answer:
See explanation
Explanation:
Let us have it behind our minds that the dielectric constant reveals the degree of polarity of a molecule. This implies that the more polar a molecule is, the greater its dielectric constant.
Chloroform is a polar molecule while carbon tetrachloride is a nonpolar molecule due to its symmetrical nature. Thus Chloroform has a greater degree of polarity and consequently a higher dielectric constant.
Methanol is more polar than ethanol because polarity of the molecule decreases as more CH2s are added to the molecule, that is, polarity of the molecule decreases with increase in the length of the carbon chain. Since methanol is more polar than ethanol, it should have a greater dielectric constant.
Again, the presence of more akyl groups in acetone makes it less polar than formamide. Consequently, formamide has a greater dielectric constant than acetone.
