1.00147g of of cobalt-60 remain after 104.7 min if you start with 1024g.
According to nuclear decay [tex]N_{t} = N_{0 } e^[/tex]^-λt
for half-life ----[tex]t_{\frac{1}{2} }[/tex] = 0.693/λ
half-life of cobalt [tex]t_{\frac{1}{2} }[/tex] = 10.47
initial amount [tex]N_{0}[/tex] = 1024g.
t = 104.7 min
final product [tex]N_{t}[/tex] =?
[tex]t_{\frac{1}{2} }[/tex] = 0.69/λ ( according to half-life)
10.47 = 0.693/λ
λ = 0.693/10.47 [tex]min^{-1}[/tex]
[tex]N_{t} = N_{0 } e^[/tex]^-λt
[tex]N_{t}[/tex] = 1024[tex]\times e^{\frac{-0.693}{10.47} } \times 104.7 min[/tex]
[tex]N_{t}[/tex] = 1024 g[tex]\times e^{-6.93}[/tex]
[tex]N_{t}[/tex] = 1.00147g
What is half-life?Half-life is the time it takes for a quantity to decrease to half its original value. This term is often used in nuclear physics to describe how quickly unstable atoms decay radioactively or how long stable atoms last. The term is also used more generally to describe any type of exponential decay.
The half-life of a radioactive isotope is the time required for half of the radioactive isotope to decay. The half-life of a given radioactive isotope is constant. it is unaffected by conditions and is independent of the initial amount of that isotope.
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Which of these are true situations that could be explained by the kinetic molecular theory?Select all that apply.
Kinect-molecular theory hypothesis:
- The formation of a gas occurs by a large number of molecules;
- Gas molecules have a negligible dimension, which means that the volume occupied by them is very small, almost insignificant;
- These gases move in a discontinuous and random way, thus occupying the entire volume of the container where they are found, having a rectilinear and uniformly varied movement;
- They are independent, they only interact with each other when a collision occurs;
- Collisions between molecules and molecules and between molecules and container walls are elastic collisions, which cause the kinetic energy of the molecules to remain constant.
Having seen these statements, the answers can only be:
The warmer a glass of water, the faster a drop of ink will spread through the water.
The colder a room is, the longer it would take to smell a spray of perfume from the other side of the room.
identify an element that has similar chemical properties as those of the element krypton (K).
True or false; The amount of energy required to heat 10 grams of water by 15 degreesCelsius is greater than that required to heat 10 grams of aluminum from15 degrees Celsius.
To answer this question we have to compare the specific heats of each substance.
The specific heat of a substance is the amount of energy required to make 1 gram of a substance increase its temperature by 1 °C. The greater the specific heat of a substance the more energy it will be required to heat it up.
The specific heat of water is 4.18J/g°C and the specific heat of aluminum is 0.897J/g°C.
It means that the amount of energy required to heat water is greater than the one to heat aluminum.
It means that the answer is TRUE.
What makes water a polar molecule? options:A) The equal forces between oxygen and hydrogenB) The liquid nature of waterC) The uneven bend in the bond between oxygen and hydrogenD) The ionic bond between oxygen and hydrogen
The polarity of a molecule is given by the difference in charges, hydrogen has a slightly positive charge and oxygen has a negative charge. Its electronegativity difference between hydrogen and oxygen is less than 1.7 making the bond a covalent bond.
That said, we can rule out options A and D. Now, the state of matter does not affect the polarity of the molecule, so option B will also be incorrect.
The correct option will be C, since there is a difference in charges that makes water polar.
Answer: C) The uneven bend in the bond between oxygen and hydrogen
Classify each of the following chemical reactions as a synthesis decomposition and single displacement or double displacement reaction
1. Synthesis reaction : there is only 1 product formed from 2 or more reactant
E.g:
[tex]H_2(g)+N_2(g)\text{ }\Rightarrow2NH_3(g)\text{ }[/tex]2. Decomposition : reaction that occurs in presence of UV light and only 1 reactant that decomposes into 2 or more products.
E.g:
[tex]CH_3Br(g)+UV_{light}\Rightarrow CH_3(g)\text{ + Br (g)}[/tex]3. Single displacement : reaction that occurs when 1 reactant displaces other reactant from its compound:
E.g:
[tex]Zn(s)+CoCl_2(aq)\text{ }\Rightarrow ZnCl_2(aq)\text{ + Co(s)}[/tex]4. Double displacement : reaction that occurs when both reactant displaces each other.
E.g :
[tex]K_2S(aq)+Co(NO_3)_2\Rightarrow2KNO_3(aq)\text{ + }CoS(s)\text{ }[/tex]the partial negative charge at one end of a water molecule is attracted to the partial positive charge of another water molecule. what is this attraction called?
Hydrogen bonding is formed when the partial negative charge at one end of a water molecule is attracted to the partial positive charge of another water molecule
Hydrogen bonding is a potent intermolecular force. In a water molecule, a partial negative charge is formed due to the oxygen, which is electro-negative.This oxygen gets attracted towards the positively charged Hydrogen, thus partial charges are shared between these two atoms of two different molecules.An electrostatic force is created between these molecules which helps in attraction of the partial charges.A hydrogen bond is formed between the water molecules which is formed due to hydrogen bonding. This kind of bond is formed between hydrogen atom and an electronegative atom, typically fluorine (F), nitrogen (N), or oxygen (O).Thus, when the partial negative charge at one end of a water molecule is attracted to the partial positive charge of another water molecule, hydrogen bonding is formed.
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What is the molarity of ions in a 0.561 M solution of Ca(OH)₂
assuming the compound dissociates completely?
For each particle (molecule) of Ca(OH)2 that was present, assuming full dissociation of the complex, you would get two particles (ions). CaO + H2O equals Ca(OH)2 (2 particles)
A 0.561 M solution contains 0.561 moles of Ca(OH)2 per kilogram of solvent. Ions' molality would be 2 x 0.561m = 1.122m.
How is an ion's molarity determined?The most used unit for expressing solution concentration is molarity (M), which is calculated by dividing the solute concentration in moles by the volume of the solution in liters: M stands for moles of solute per liter of solution.
What does ion molality mean?The kilograms of solvent divided by the moles of ions in the solution is the molality. As an illustration, if You will have 1.0 molal concentration of sodium chloride, for instance, if 1.0 moles of sodium chloride are dissolved in 1.0 kilogram of solution.
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6.5 grams of zinc reacted with hydrochloric acid. Calculate how many grams of hydrogen were released. a) 0.1 g. b) 0.2 g. c) 1.0 g. d) 2.0 g.
0.2 grams
ExplanationsThe balanced reaction between zinc and hydrochloric acid is given as:
[tex]Zn+2HCl\rightarrow ZnCl_2+H_2[/tex]Given the following parameters
Mass of Zinc = 6.5grams
Determine the mole of Zinc
Mole of Zn = mass/molar mass
Mole of Zn = 6.5/65.38
Mole of Zn = 0.0994moles
According to stoichiometry, 1 mole of Zinc produced 1 mole of hydrogen gas, hence the mole of hydrogen gas required will be 0.0994moles
Determine the mass of hydrogen gas produced
[tex]\begin{gathered} Mass\text{ of H}_2=mole\times molar\text{ mass} \\ Mass\text{ of H}_2=0.0944moles\times2.016 \\ Mass\text{ of H}_2=0.19g\approx0.2grams \end{gathered}[/tex]Hence the mass of hydrogen that were released is 0.2 grams
does lead melt in atoms or molecules
Answer:
Atoms
Explanation:
Answer:
atoms
Explanation:
its right, trust
Potential Molecular TheoryThere are 500 grams of Kl in a volumetric flask. It is dissolved in 1 liter of water. What is the molarity?3.141 M3.012 M0.500 M500.000 M20A precipitate is formed when two solutions are mixed. This would only occur if
Molarity or molar concentration is a measure of the concentration of a chemical species, of a solute in a solution, using as units, number of moles, and volume in liters. The formula for Molarity is:
M = n/V
Where:
n = number of moles
V = volume in Liters, 1 Liter
But we need to find the number of moles, we will do so by using its molar mass, KI = 166g/mol and the given mass in the question, 500g grams
166g = 1 mol
500g = x moles
x = 3.012 moles
Now we can use the Molarity formula
M = 3.012/1
M = 3.012 M, this is the molar concentration of the solution, 2
Consider the balanced thermochemical equation given below: W(s) + 3 H2O(g) → WO3(s) + 3 H2(g) ∆Η° = –125.9 kJ How many grams of H2 were produced when 377 kJ of heat was produced?
Answer:
Explanation:Consider the balanced thermochemical equation given below: AH = -125.9 kJ W(s) + 3 H2O(g) WO3(s) + 3 H2(g) If a mass of 94.6 g H2 is produced, what is the enthalpy change? Express your answer in kJ. Express your answer to the correct number of significant figure, in scientific notation and include the unit with
Which of the following elements would have chemical properties similar to those of Na?O Ne KBr
Ne is a noble gas, O is a non metal and Br is an halogen.
K is a metal that belongs to the same group as Na, it means that they have similar chemical properties.
It means that the answer is K.
Calculate the mass (in g) of 5.86x10^20 SO3 molecules.
Answer
0.0779 g SO₃
Procedure
To solve this question, you will need to use the Avogadro's number equivalent to 6.02214 x 10^23 molecules/ mol, and then the molecular weight in grams per mole for the SO₃.
[tex]5.86\times10^{20}\text{ molecules SO}_3\frac{1\text{ mol SO}_3}{6.02214\text{ x 10}^{23}\text{molecules SO}_3}\frac{80.06\text{ g SO}_3}{1\text{ mol SO}_3}=0.0779\text{ g SO}_3[/tex]How many milliliters of 0.165 M HCL are needed to neutralize completely 25.0 mL of 0.101 M Ba(OH)2
We have a neutralization between the HCl (acid) and Ba(OH)2 (base):
To calculate the mL asked, we need to use the next formula:
M1 x V1 = M2 x V2 (1)
We assign number 1 to HCl and number 2 to Ba(OH)2
Remember: M molarity and V volume
-----------------
Data:
We know M1 = 0.165 M (HCl) and M2 = 0.101 M, V2 = 25.0 mL.
-----------------
Procedure:
We clear V1 from (1):
V1 = M2 x V2/M1 = 0.101 M x 25.0 mL/0.165 M = 15.3 mL
Answer: V1 = 15.3 mL
12: from the following list, decide whether the following are Arrhenius bases or acids.•HCl•NaOh•HBr•H2SO4•NH4OH•H3PO4•HNO3•LiOH•Ba(OH)2•CsOH•HF•KOH
Answer:
The Arrhenius acids in the list are:
HCl, HBr , H2SO4 , H3PO4 , HNO3 , HF
The Arrhenius bases are:
NaOH , NH4OH , LiOH , Ba(OH)2 , CsOH and KOH
Explanation:
An Arrhenius acid increases the concentration of H+ ions while an Arrhenius acid increases the concentration of OH- ions
Thus, an Arrhenius acid would yield H+ ions on ionization while an Arrhenius base will yield OH- ions on ionization
The Arrhenius acids in the list are:
HCl, HBr , H2SO4 , H3PO4 , HNO3 , HF
The Arrhenius bases are:
NaOH , NH4OH , LiOH , Ba(OH)2 , CsOH and KOH
3.(a) Draw the following five-carbon hydrocarbons:•Pentane•Pentene•Pentyne(e)Classify each molecule and explain the differences between them. (Classes of organic molecules include alkanes, alkenes, alkynes, alcohols, carboxylic acids, aldehydes, ketones, esters, ethers, amines, and amides.)
Structural formulas are ways atoms and elements are arranged in a molecule. The structural formula of pentane, pentene, and pentyne are as shown below;
Pentane - C5H12
Pentene - C5H10
Pentyne - C5H8
e) Pentane is an alkane compound with a general formula CnH2n+2. The chemical formula of pentane is C5H12. There are only single bonds between the C-H atoms in the molecule.
Pentene is an alkene compound with a general formula of CnH2n. The chemical formula of pentene is C5H10. There is a double bond present between the C=H atoms. This double bond shows that the compound is an alkene.
Pentyne is an alkyne compound with a general formula of CnH2n-2. The chemical formula of pentene is C5H8. There is a triple bond present between the Carbon Hydrogen atoms. This presence of a triple bond shows that the molecule is an alkyne compound.
How many moles of carbon dioxide are formed when reacting with 36 moles of oxygen?
1) Chemical equation
[tex]CH_4+2O_2\rightarrow CO_2+2H_2O[/tex]2) Moles of CO2 produced oxygen reacts
The molar ratio
2 mol O2: 1 mol CO2
[tex]molCO_2_{}=36molO_2\cdot\frac{1molCO_2}{2molO_2}=18molCO_2[/tex]If 36 mol O2 reacts, it will produce 18 mol CO2.
.
Calculate the number of moles of magnesium, chlorine, and oxygen atoms in 8.30 moles of magnesium perchlorate,Mg(Cl04)2Express the number of moles of Mg, Cl, and O atoms numerically, separated by commas.moles of Mg, CI, O =
The question requires us to calculate the number of moles of each element (magnesium, chlorine and oxygen) in 8.30 moles of the compound magnesium perchlorate (Mg(ClO4)2).
From the molecular formula of magnesium perchlorate we can take the following information:
- in 1 mol of Mg(ClO4)2, there is only 1 mol of Mg;
- in 1 mol of Mg(ClO4)2, there are 2 moles of Cl;
- in 1 mol of Mg(ClO4)2, there are 8 moles of O.
With the information above, and knowing that the amount of Mg(ClO4)2 given by the question was 8.30 moles, we can calculate the amount, in moles, of each element:
1 mol Mg(ClO4)2 --------------- 1 mol Mg
8.30 mol Mg(ClO4)2 ---------- x = 8.30 mol Mg
1 mol Mg(ClO4)2 --------------- 2 mol Cl
8.30 mol Mg(ClO4)2 ---------- y = 2 x 8.30 mol Cl = 16.6 mol Cl
1 mol Mg(ClO4)2 --------------- 8 mol O
8.30 mol Mg(ClO4)2 ---------- z = 8 x 8.30 mol O = 66.4 mol O
Therefore, there are 8.30, 16.6 and 66.4 moles of Mg, Cl and O in 8.30 moles of magnesium perssufate.
If I have 10.0g of Mg, what is my theoretical yield of MgCl2
Explanation:
First, let's write the balanced equation of formation of MgCl2 from Mg and Cl2:
Mg + Cl2 → MgCl2
Now let's transform 10.0g of Mg into moles, using the following formula: moles = mass/molar mass
molar mass of Mg = 24.3 g/mol
moles = 10/24.3
moles = 0.412 moles
Now we use the equation ratio between Mg and MgCl2 to find the quantity of MgCl2 in moles.
1 mole of Mg produces 1 mole of MgCl2.
So 0.412 moles of Mg produces 0.412 moles of MgCl2.
Now we transform 0.412 moles of MgCl2 into mass using the following formula: mass = moles x molar mass
Molar mass of MgCl2: 24.3 + (2*35.45) = 95.21 g/mol
Mass = 0.412 * 95.21
Mass = 39.2 g
Answer: The theoretical yield of MgCl2 is 39.2 g.
Create a table of different types of radioactive decay and the changes that result in each.
answer and explanation
Radioactivity is the emission of ionizing radiation from nuclear decay. there are three types of radioactive decay.
alpha decay
in alpha decay an alpha particle is released. In the parent atom, the atomic number decreases by 2 and the atomic mass decreases by 4
beta decay
in beta decay a beta particle is released, the atomic number is unchanged and the atomic mass increases by 1
gamma decay
in gamma decay, energy is released as gamma rays from an excited nuclear state. the atomic mass and atomic number remain unchanged.
What is the percent yield if 15.5 g SO2 is obtained from the reaction of 42.5 g of O2 with excess ZNS according to the following equation 2ZnS (s) + 3O2 -> 2ZnO (s) + 2 SO2(g)
Answer:
Percent yield = 27.3%.
Explanation:
First, let's write the chemical equation:
[tex]2ZnS+3O_2\rightarrow2ZnO+2SO_2.[/tex]The limiting reactant, in this case, would be O2 because we have an excess of ZnS. So, we have to convert 42.5 g of O2 to moles. Remember that the molar mass of O2 is 32 g/mol (you can calculate the molar mass of a compound using the periodic table). The conversion will be:
[tex]42.5\text{ g O}_2\cdot\frac{1\text{ mol O}_2}{32\text{ g O}_2}=1.33\text{ moles O}_2.[/tex]With this value, we're going to find the number of moles of SO2 produced by 1.33 moles of O2. You can see in the chemical equation that 3 moles of O2 reacted produces 2 moles of SO2, so the calculation would look like this:
[tex]1.33\text{ moles O}_2\cdot\frac{2\text{ moles SO}_2}{3\text{ moles O}_2}=0.887\text{ moles SO}_2.[/tex]The next step is to find the mass of SO2 based on its number of moles and the molar mass of SO2 which is 64 g/mol, like this:
[tex]0.887\text{ moles SO}_2\cdot\frac{64\text{ g SO}_2}{1\text{ mol SO}_2}=56.8\text{ g SO}_2.[/tex]And finally, we replace the values that we have in the formula of percent yield:
[tex]\%\text{ yield }=\frac{experimental\text{ yield}}{theoretic\text{al yield}}\cdot100\%.[/tex]Our experimental yield is the mass that we obtained of SO2 which is 15.5 g and the theoretical yield is the mass that we found through stoichiometry which is 56.8g:
[tex]\%\text{ yield}=\frac{15.5\text{ g}}{56.8\text{ g}}\cdot100\%\approx27.3\%.[/tex]The percent yield of this reaction would be 27.3%
Define hydrogen bonding and explain how hydrogen are bonding involved in the
transfer of genetic material.
Answer:
Hydrogen bonding is a special type of dipole-dipole attraction between molecules, not a covalent bond to a hydrogen atom. It results from the attractive force between a hydrogen atom covalently bonded to a very electronegative atom such as a N, O, or F atom and another very electronegative atom.
Explanation:
Question 7 of 10What makes up an ionic compound?O A. A positive cation and a negative anionB. A negative anion and a negative anionOC. A positive anion and a negative cationOD. A positive cation and a positive anionаSUBMIT
A ionic compound is made of two ions, one with positive charge and the other one with a negative charge.
The ion with positive charge is known as cation and the one with negative charge is known a anion.
It means that the correct answer is A. A positive cation and a negative anion.
Synthesize Information If you calculate the percent composition of elements in a compound, is there enough information to determine the empirical formula for the compound? If yes, how? If no, improve the model by identifying and explaining additional information needed to identify the compound.
If you only have the percent composition of each element in a give compound, you can't determine yet the empirical formular for the compound. The problem is, the percent composition only gives relative numbers for each element. What can be determined is the empirical stochiometry of one element relative to the others.
For example, supose you have a compound with element X and Y, with the percent composition you can determine how much X you have relative to how much Y you have. Say you determine that for each 2 X you have 3 Y, the formula can be X₂Y₃ but it can also be X₄Y₆ or even othre possibilities.
To determine the empirical formula you need to know how many of one of the elements you have in each compound. A common way of getting the empirical formula is to use the percent composition and, in addition, the molar mass of the compound, which will make it possible to get the empirical formula from the relative ratios of each element you have.
In an experiment 25 grams of chloroform and 25 grams of chlorine were mixed. Which is the limiting reagent? I picked C but I’m not sure if I’m correct
In this question, we have to find the limiting reactant based on the following reaction:
CHCl3 + Cl2 -> CCl4 + HCl
We have:
25 grams of CHCl3
25 grams of Cl2
The molar ratio between these two compounds is 1:1, 1 mol of CHCl3 for 1 mol of Cl2
Now we have to find the number of moles of each reactant, let's start with CHCl3, we will use its molar mass, 119.38g/mol:
119.38g = 1 mol
25g = x moles
119.38x = 25
x = 25/119.38
x = 0.209 moles of CHCl3
According to the molar ratio, if we have 0.209 moles of CHCl3, we will also have 0.209 moles of Cl2, which has a molar mass of 70.9g/mol
Let's find the mass of 0.209 moles of Cl2:
70.9g = 1 mol
x grams = 0.209 moles of Cl2
x = 14.81 grams
We only need 14.81 grams of Cl2 to react with 25 grams of CHCl3, since we have more Cl2 than we actually need, this makes Cl2 the excess reactant, and CHCl3 will be the limiting reactant. Letter C
I need help with filling out the cubes and emery’s, basically the Application: Assigning Oxidation numbers (shown in the photo)
According to the explanation about oxidizing and reducing agents from the previous session, we will find the answers to this question as well
Oxidation numbers are mostly found in previously made tables, there are plenty of tables where you can see the oxidation numbers for almost every element, a few rules to have in mind is H is usually +1, O is -2, Halogens are -1, group 1A metals are +1, transition metals are the ones that will shift a lot
1. Sn + 2 HCl -> SnCl2 + H2, this is the properly balanced equation
REACTANTS
Sn = 0, since it's a lone element in the reaction we assume its charge is 0 because is stable
H = +1
Cl = -1, it's a halogen
PRODUCTS
Sn = +2, we see now that Sn was oxidized and now has a positive charge
Cl = still -1
H2 = 0, was reduced, now with a 0 charge
2. 2 NaBr + Cl2 -> 2 NaCl + Br2
REACTANTS
Na = +1, metal from group 1A
Br = -1, halogen
Cl2 = 0 stable element
PRODUCTS
Na = +1
Cl = -1, it will be reduced
Br = 0, it will be oxidized
3. SiCl4 + 2 Mg -> 2 MgCl2 + Si
REACTANTS
Si = +4
Cl = -1
Mg = 0
PRODUCTS
Mg = +2, it will be oxidized
Cl = -1
Si = 0, it will be reduced
A gas has a volume of 1.82 L at-30°C and 131 kPa. At what temperature would the gasoccupy 1.3 L at 233 kPa?Answer in units of°C.
To solve this problem we can use the Ideal gas law:
[tex]\frac{P_1\cdot V_1}{T_1}=\frac{P_2V_2}{T_2}[/tex]The problem give us de following information:
P1= 131kPa
V1=1.82L
T1=-30°C= 243.15 K
P2= 233 kPa
V2= 1.3L
Then we just have to solve for T2 and use the information provided:
[tex]T_2=\frac{P_2\cdot V_2}{P_1\cdot V_1}\cdot T_1=\frac{233\text{ kPa}\cdot1.3L}{131kPa\cdot1.82L}\cdot243.15K=308.91K=35.76°C[/tex]Then the answer is T2=35.76°C
How many copper atoms are in a pure copper statue with a mass of 187 kg?
Avogadro's number states that:
1 mol of Cu = 63.54 g of Cu = 6.02x10^23 atoms of Cu
Now, we proceed like this:
1 kg = 1000 g ===> 187 kg = 187,000 g
63.54 g Cu -------- 6.02x10^23 atoms of Cu
187,000 g Cu -------- X
X = 1.77x10^27 atoms Cu
Answer: 1.77x10^27 atoms Cu
Abed found fingerprints at a crime scene that match fingerprints that were taken from the suspect. What does this MOST likely mean?
A.
The suspect’s fingerprints match someone else’s.
B.
All 150 ridge characteristics are identical.
C.
The suspect touched something at the crime scene.
D.
At least three different points were a perfect match.
Answer:
C
Explanation:
Because the suspect touched something at the crime scene and thus he's fingerprint are matching
a sample of a gas is at STP and it’s temperature remains constant. if the pressure decreases what will happen to the volume
Explanation
There are said to have two different conditions of a gas.
First condition is STP which means: pressure = 1 atm and temperature (absolute) = 0 °C + 273 = 273 K
-------------
It is said that the temperature remains constant, therefore we can apply Boyle's law which states that the pressure of a gas tends to decrease as the volume of the container increases.