A solution of Calcium Chloride was made, we are asked to find the concentration of the initial solution.
We will apply the following equation to find it:
[tex]C_1V_1=C_2V_2[/tex]Where,
C1 is the initial concentration we have to find
V1 is the initial volume, 45mL
C2 is the final concentration, 0.182M
V2 is the final volume, 50. mL
We clear C1 and replace the known data;
[tex]C_1=\frac{C_2V_2}{V_1}[/tex][tex]\begin{gathered} C_1=\frac{0.182M\times50.mL}{45mL} \\ C_1=0.202M \end{gathered}[/tex]The molarity of the stock solution is 0.202M
Answer: 0.202M
A solution is made by dissolving4.87 g of potassium nitrate in waterto a final volume of 86.4 mL solution.What is the weight/weight % orpercent by mass of the solute?Use 1.00 g/mL for the density of the solution.Enter text here
Answer
The weight/weight % of solute = 5.3%
Explanation
Given
Mass of solute (potassium nitrate) = 4.87 g
Volume of solvent (water) = 86.4 mL
Density of water = 1.00 g/mL
Required: Weight/weight% of the solute
Solution
Step 1: Covert the volume of water to mass
mass = density x volume
mass = 1.00 g/mL x 86.4 mL
mass = 86.4 g
Step 2: Calculate the weight/weight % of the solute
Mass % solute = [mass of solute/(mass of solute + mass of solvent)] x 100
Mass % solute = 4.87g/(4.87 + 86.4)
Mass % solute = 5.3%
JWhat did Rutherford’s model of the atom include that Thomson’s model did not have?
a nucleus
energy levels
electron clouds
smaller particles
Answer:
Rutherford's model of the atom included the nucleus, something lacking in Thomson's model. Rutherford's inclusion of the nucleus came about after his discovery of the nucleus of the atom in 1911. He was testing J.J. Thomson's Plum Pudding model by directing a beam of alpha particles toward a thin sheet of gold foil.
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Patricia wants to examine the morphology of a hair sample. What is the BEST way for her to accomplish this task?
A.
Send the sample away to a lab for DNA testing.
B.
Observe the sample under a high-powered microscope.
C.
Add a solution to the hair to see if it reacts.
D.
Use a Hemastix strip to perform A-B-O testing.
The best way for her to accomplish the task of evaluating a hair strip is DNA testing. Hence, option A is correct.
What is DNA testing?The DNA testing in forensic laboratories include extract the DNA strands from the sample and strictly evaluate it some reagents and color indicators.
Hair analysis involves examining the DNA of cells linked to the hair's root as well as the hair's structure. It can be used to determine a person's family relationship. It is possible to use forensic hair analysis to identify a person who may have been at a crime scene. Hair samples are examined under a microscope and evaluated using particular chemicals.
Additionally, metal poisoning from lead or mercury can be detected through hair analysis. However, this form of testing often does not involve hair analysis alone.
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how do i calculate the molar mass of 5 and 65. K2Cr2O76. C12H22O11
To calculate the molar mass of a compound, we need to find at the periodic table the atomic mass of each element that belongs to the compound and then we multiply for the quantity of atoms of it.
So, for:
5. K2Cr2O7:
K = 39 g/mol
Cr = 52 g/mol
O = 16 g/mol
(2x39) + (2x52) + (7x16) = 78 + 104 + 112 = 294 g/mol
Molar mass of K2Cr2O7 = 294 g/mol
6. C12H22O11
C = 12 g/mol
H = 1 g/mol
O = 16 g/mol
(12x12) + (22x1) + (11x16) = 144 + 22 + 176 = 342 g/mol
Molar mass of C12H22O11 = 342 g/mol
If 21.5 g of LiCl are dissolved 450.0 g of water at 20.0 °C in an insulated container, a temperature change is observed. The ∆H of solution of LiCl is -37.0 kJ/mol. Assuming that the specific heat of the solution is 4.184 J/(g°C), and that no heat is gained or lost by the container, what will be the final temperature of the solution?
The final temperature of the solution will be 29.5 °C.
What is the heat released when 21.5 g of LiCl is dissolved completely in water?The heat released when 21.5 g of LiCl is dissolved completely in water is determined from the enthalpy change, ∆H of the solution of LiCl as follows;
Moles of LiCl in 21.5 g = mass/ molar mass
molar mas of LiCl = 42.5 g/mol
Moles of LiCl in 21.5 g = 21.5/42.5
Moles of LiCl in 21.5 g = 0.506 moles
Heat released = 0.506 * -37.0 kJ/mol
Heat released = 18.722 kJ or 18722 J
Heat released = heat gained by solution
Temperature change of the solution = heat gained / mass * specific heat capacitymass of solution = 450 + 21.5
mass of solution = 471.5 g
Temperature change of the solution = 18722 / (471.5 * 4.184)
Temperature change of the solution = 9.5 °C
Final temperature of the solution = 20 °C + 9.5 °C
Final temperature of the solution =29.5 °C
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How many joules of heat are needed to raise the temperature of 100 g of iron from 23°C to 33°C, if the specific heat of iron is 0.45 J/g°C
Joules of heat are needed to raise the temperature of 100 g of iron from 23°C to 33°C, if the specific heat of iron is 0.45 J/g°C is 450 J.
Given that :
The specific heat capacity expression is given as :
Q = m cΔT
Q = heat energy
m = mass = 100 g
c = specific heat = 0.45 J/g °C
ΔT = change in temperature = 33 °C - 23 °C = 10 °C
substituting the values in the formula:
Q = m cΔT
Q = 100 g × 0.45 J/g °C × 10 °C
Q = 450 J
Thus, Joules of heat are needed to raise the temperature of 100 g of iron from 23°C to 33°C, if the specific heat of iron is 0.45 J/g°C is 450 J.
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How many atoms are in 275 grams of iron (III) hydroxide. Include units and name of atom/molecule.
To calculate the number of atoms of any compound it is necessary to use the Avogadro constant. This is a constant of proportion between the amount of matter and the number of entities that are linked to that amount. These entities can be atoms, molecules, ions, electrons, protons, neutrons. The value of the Avogrado constant is 6.022 x 10^23 mol^-1.
So to calculate the number of atoms in 275 grams of iron (III) hydroxide:
- First you need to transform grams into moles
- transform moles into atoms/molecule using Avogrado constant.
- To transform 275 grams of Fe(OH)₃ you need to use the molecular mass of Fe(OH)₃ and the following equation: mole = mass/molar mass
Molecular mass of Fe(OH)₃:
Fe - 55.85
O - 16
H - 1
(1x55.85) + (3x16) + (3x1) = 106.86 g/mol
Replace the value in the equation:
mole = 250/106.86
mole = 2.34 mole of Fe(OH)₃
- Now, let's solve the number of molecules of Fe(OH)₃ into 2.34 mole of Fe(OH)₃:
6.022 x 10^23 molecule --- 1 mol
x molecule ---- 2.34 mole
x = 1.41 x 10^24 molecules of Fe(OH)₃
Answer: There are 1.41 x 10^24 molecules of Fe(OH)₃
ectQuestion 13What is being reduced in the following reaction ?C2H4(g) + 302(g) → 2CO2(g) + 2H2O(g)C2H4H20No reduction or oxidation is occurringCO2
Step 1
The reaction is written and balanced as:
C2H4(g) + 302(g) → 2CO2(g) + 2H2O(g)
Step 2
Oxidation states are analyzed
For O2)
On the left, its oxidation state is 0 (O2)
On the right, it is -2 (H2O)
Step 3
The half-reaction is written as:
6 O + 12 e- => 6 O2-
Therefore, O2 is being reduced
Answer: O2
A -13.68 gram of sample of iron is heated in the presence of excess fluorine. A metal Fluoride is formed with a mass of 27.64g. Determine the empirical formula of the metal fluoride.
Explanation:
A 13.68 g sample of iron is reacted in presence of excess fluorine and an iron fluoride with a mass of 27.64 g is formed.
We have to find the empirical formula of our compound. This compound has two elements: Fe and F. We can express it like:
metal fluoride = FeₐFₓ
Where a is the subscript of Fe and x is the subscript for F.
First we have to find the mass of F present in the compound. We know that our compound has a total mass of 27.64 g and the mass of Fe present is 13.68 g. Since it only has two elements we can find the mass of F.
mass of sample = mass of Fe + mass of F
mass of F = mass of sample - mass of Fe
mass of F = 27.64 g - 13.68 g
mass of F = 13.96 g
So we found that our sample has 13.96 g of F and 13.68 g of Fe. Now we can determine the number of moles of each element that are present in the sample by using their molar masses.
molar mass of Fe = 55.85 g/mol
molar mass of F = 19.00 g/mol
moles of Fe = 13.68 g * 1 mol/(55.85 g)
moles of Fe = 0.245 moles
moles of F = 13.96 g * 1 mol/(19 g/mol)
moles of F = 0.735 moles
By definition the empirical formula is "simplest whole number ratio of atoms present in a compound". So if we want to find the ratio between them we have to divide both of them by the smallest number.
a = subscript of Fe = 0.245/0.245 = 1
x = subscript of F = 0.735/0.245 = 3
So the empirical formula of our compound is:
empirical formula = FeₐFₓ
empirical formula = FeF₃
Answer: empirical formula = FeF₃
Why is reproducibility so important to scientistis
Answer: They serve as proof that an established and documented work can be verified, repeated, and reproduced.
Explanation: Reproducibility and research integrity are essential tenets of every scientific study and discovery. They serve as proof that an established and documented work can be verified, repeated, and reproduced. New knowledge in biomedical science is built on the shoulders of established and proven principles.
Answer:
Evidence of accuracy
Explanation:
it creates new opportunities for insights and facilitates innovation in terms of scientific knowledge.
An experiment begins
with 87.5g of
potassium and 13.2g of
chlorine. What is the
experiment mass of
the product?
The experiment mass of the product is 28.1g
What is mass ?
Mass is a physical body's total amount of matter. It also serves as a gauge for the body's inertia, or resistance to acceleration (change in velocity) in the presence of a net force. The strength of an object's gravitational pull to other bodies is also influenced by its mass.
The kilogramme is the primary mass unit in the SI (kg). Although weight is frequently measured using a spring scale rather than a balancing scale and compared directly with known masses, mass is not the same as weight in physics.
2K + Cl2 =====> 2KCl
70g Cl2 produces 2(39+35.5) = 149 g KCl
13.2g Cl2 produces 28.1g KCl
the experiment mass of the product is 28.1g
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2. 5.4 grams of carbon dioxide gas is confined to a 20.0 L container at atemperature of 32.5°C. What pressure does the gas exert? (15 kPa)
To calculate this, we will need to assume the gas behaves as an ideal gas.
So, we can use the Ideal Gas Law:
[tex]PV=nRT[/tex]Where P is the pressure, V is the volume, n is the number of moles, is the absolut temperature and R is the gas law constant.
Since we have carbon dioxide, CO₂, we need to calculate its molar mass to convert the mass to number of moles:
[tex]\begin{gathered} M_{CO_2}=(1\cdot M_C+2\cdot M_O) \\ M_{CO_2}=(1\cdot12.0107+2\cdot15.9994)g\/mol \\ M_{CO_2}=44.0095g\/mol \end{gathered}[/tex]So, the number of moles is:
[tex]\begin{gathered} M_{CO_2}=\frac{m}{n} \\ n=\frac{m}{M_{CO_{2}}}=\frac{5.4g}{44.0095g\/mol}=0.1227\ldots mol\approx0.12mol \end{gathered}[/tex]Also, we need to convert the temperature to absolute temperature, so we can convert it to K by adding 273.15 to the degree celcius temperature:
[tex]T=32.5\degree C=(32.5+273.15)K=305.65K[/tex]Now, we need to use the constant R that has the unit we want. We have K for temperature, mol for number of moles and L for volume. Is we want the pressure in kPa, we need to use the R constant with units L*kPa/(K*mol), which have the value:
[tex]R\approx8.31446\frac{L\cdot kPa}{K\cdot mol}[/tex]So, solving the equation for P and substituting the values, we have:
[tex]\begin{gathered} PV=nRT \\ P=\frac{nRT}{V} \\ P=\frac{0.12mol\cdot8.31446L\cdot kPa\cdot K^{-1}mol^{-1}\cdot305.65K}{20.0L} \\ P=\frac{0.12\cdot8.31446\cdot305.65}{20.0}kPa \\ P=15.247\ldots kPa\approx15kPa \end{gathered}[/tex]So, the pressure is approximately 15 kPa.
What is one way an atom can become more stable?
Unstable atoms usually are very large atoms with a big nucleus, this configuration sometimes gives the atoms this unstable characteristic, which is why they decay so fast (some will decay in a matter of milliseconds), and radioactive decay is a way that atoms can find to become more stable, in this type of process, particles (alpha and beta decay) and energy (gamma decay), can be emitted from an atom in order to reach stability, therefore the best option is the 3rd option
Virginia has 11 people in the House and 2 in the Senate. How many electoral votes does it have? ________________ Where is this addressed?
The total number of electoral votes does Virginia have is 13. This addressed in congressional apportionment.
When people cast their vote, means they actually voting for the group of people called electors. Senator and representatives are equal to the number of voters in each state . According to the question , Virginia has 11 people in the house and 2 senate means 11 + 2 = 13 . the total number of electoral votes are 13. These votes are assigned by united states electoral college. In the constitution the congressional apportionment is addressed.
Thus, Virginia has 11 people in the House and 2 in the Senate. The total number of electoral votes does Virginia have is 13. This addressed in congressional apportionment.
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explain absolute entropies and it's determination in terms of heat capacity
The total entropy that a pure material would accumulate upon warming from absolute zero (where S=0) to the specific temperature is the absolute entropy of that substance at that temperature.
What is entropy?
One of the key ideas that students studying physics and chemistry need to grasp with clarity is entropy. More importantly, entropy has multiple definitions and can be used in a variety of contexts, including the thermodynamic stage, cosmology, and even economics. Entropy is a notion that mostly discusses the spontaneous changes that take place in commonplace phenomena or the universe's propensity for chaos.
Determination in terms of heat capacity
The third rule of thermodynamics has two significant ramifications: it establishes a constant reference point that enables us to measure the absolute entropy of any substance at any temperature, and it specifies the sign of the entropy of any substance at temperatures above absolute zero as positive. We look at two different approaches to calculating S for a reaction or a physical change in this section.
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Based on the thermodynamic properties provided for water, determine the energy change when the temperature of 0.950 kg of water decreased from 103 °C to 60.5 °C.
Property Value Units
Melting point 0 °C
Boiling point 100.0 °C
ΔHfus 6.01 kJ/mol
ΔHvap 40.67 kJ/mol
cp (s) 37.1 J/mol · °C
cp (l) 75.3 J/mol · °C
cp (g) 33.6 J/mol · °C
The energy change when the temperature of 0.950 kg of water decreased from 103 °C to 60.5 °C is 2308.87 kJ.
What is the heat energy change when the temperature of 0.950 kg of water decreased from 103 °C to 60.5 °C?The heat energy change when the temperature of 0.950 kg of water decreased from 103 °C to 60.5 °C is determined from the formulas below:
Heat change 1 = Heat capacity as gas * moles * temperature change
Heat change 2 = Heat of vaporization, ΔHvap * moles
Heat change 3 = Heat capacity as liquid, Cp (l) * moles * temperature change
moles of water = 950 kg * 1000 g/kg * 1 mol/ 18g = 52.78 mole
Heat change 1 = 33.6 * 52.78 * (103 - 100) = 5320.224 J
Heat change 2 = 40.67 * 1000 * 52.78 = 2146562.6 J
Heat change 3 = 75.3 * 52.78 * (100 - 60.5) = 156986.193 J
Total heat change = 5320.224 J + 2146562.6 J + 156986.193 J
Total heat change = 2308869.017 J = 2308.87 kJ
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dry cleaners use tetrachloroethylene (C2CL4) to dissolve oil and grease because C2CL4 is
Answer: Tetrachloroethylene is an nonpolar molecule.
Which state of matter is being described below?It cannot be squashed easily, will not spread out & is high densityA. GasB. SolidC. LiquidD. Plasma
There are 3 main states of matter: gas, solid, and liquid.
The solid is characterized by its rigid structure, its high density (it means that's there's a lot of mass per unit of volume). Also, it doesn't take the container's shape as a liquid does.
Then, the description corresponds to the solid state (option B).
The combustion of liquid ethanol (C2H, OH)produces carbon dioxide and water. After 5.8 mLof ethanol (density = 0.789 g/mL) was allowed toburn in the presence of 12.5 g of oxygen gas, 3.10mL of water (density = 1.00 g/mL) was collected.
Answer
Explanation
Given data:
A 0.016773-m^3 tank contains 1kg of refrigerant-134a at 110C. Determine the pressure of the refrigerant using (a) the ideal-gas equation, (b) the generalized compressibility chart, and (c) the refrigerant tables.
Answers:(a)1.861MPa,(b)1.583MPa,(c)1.6MPa
The pressure of the refrigerant using the ideal-gas equation is 1.861 MPa, the generalized compressibility chart is 1.583 MPa and the refrigerant tables is 1.6 MPa.
What is ideal gas equation?Ideal gas equation is defined as the state equation for a fictitious perfect gas. Although it has significant drawbacks, it is a decent approximation of the behavior of many gases under various conditions.
Ideal gas equation is expressed as
PV = nRT
By using Ideal gas equation
P x 0.016773 = 1 x 81.49 x 483
P = 1.861 MPa
By using generalized compressibility chart
For r134a
Temperature = 374.2 K
Pressure = 4.06 MPa
vR = V / R x Tc / Pc
= 0.016773 / 81.49 x ( 374.2 / 4.06 x 10⁶ )
= 2.2332
Tr = T/Tc = 383 / 374.2 = 1.024
Therefore from the chart Z = 0.85
So, P = Z mRT / V
P = 0.85 x 1 x 81.49 x 383 / 0.016773
= 1.582 MPa
By using refrigerant tables
T = 110 C and v = 0.0167763
So, P = 1.6 MPa
Thus, the pressure of the refrigerant using the ideal-gas equation is 1.861 MPa, the generalized compressibility chart is 1.583 MPa and the refrigerant tables is 1.6 MPa.
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If an element has a mass of 56 amu, and it has 26 protons, how many neutrons are present? How many electrons?
Answer:
1. 30 neutrons
2. 26 electrons
Explanation:
The number of neutron = mass - #protons = 56 - 26 = 30
The number of electrons = #protons = 26
There are 4 moles of methane burned to produce how many moles of water? CH4+2O2=CO2+2H2O
ANSWER
8 moles of water
EXPLANATION
The major products formed when an organic compound undergo combustion reaction are water and carbon dioxide
Below is the combustion formula
[tex]\text{ C}_xH_y\text{ + x + }\frac{y}{4}O_2\text{ }\rightarrow\text{ xCO}_2\text{ + }\frac{y}{2}H_2O[/tex]In the question above, 4 moles of methane reacts with oxygen
[tex]\begin{gathered} \text{ 4CH}_4\text{ + 4+}\frac{16}{4}O_2\text{ }\rightarrow\text{ 4CO}_2\text{ + }\frac{16}{2}H_2O \\ \\ \text{ 4CH}_{4(g)}\text{ + 8O}_{2(g)}\text{ }\rightarrow\text{ 4CO}_{2(g)}\text{ + 8H}_2O(l) \end{gathered}[/tex]Therefore, 4 moles of methane will give 8 moles of water
What kind of intermolecular forces act between a chloramine (NH₂CI) molecule and an oxide (0²-) anion?Note: If there is more than one type of intermolecular force that acts, be sure to list them all, with a comma between thename of each force.
Answer
Hydrogen bonding, dipole-dipole interaction, and dispersion forces.
Explanation
The chloramine (NH₂CI) molecule has N-H bonds, so there will be hydrogen bonding. Also, NH₂Cl is a polar molecule, so there will be dipole-dipole interaction. And as with molecules like O²⁻, there will be dispersion forces.
Therefore, the kind of intermolecular forces that act between a chloramine (NH₂CI) molecule and an oxide (O²⁻) anion are hydrogen bonding, dipole-dipole interaction, and dispersion forces.
How many mols of Cl₂ are needed to make 0.6 mols of NaCl according to the
following reaction?
2Na + Cl₂ --> 2NaCl
How many groups are attached to a center atom with trigonal planar geometry? 3 groups 1 group 5 groups 4 groups
Answer:
The number of groups attached to a center atom with trigonal planar geometry is 3 groups.
Which of the following describes a physical property?Corrosiveness of sodiumToxcity of cadmiumWater when heated forms steamFlammability of hydrogen
Physical properties are the ones that describe the behavior of the substances when exposed to different physical changes.
In this case, the one that describes a physical change is water when heated forms steams. In this case water changes its state of matter but it is still the same substance, there is not chemical change, just physical.
The correct answer is Water when heated forms steams.
Ionic compound formulas must be ______ to the smallest whole number ratio
Explanation:
As an example, Let's writte some ionic compounds:
Triglycerides, waxes, and steroids are all _______ lipids because they contain only carbon, hydrogen, and oxygen.Question 20 options:A) long-chain compoundsB) methyl estersC) complexD) simple
Answer:
Explanation:
Here, we want to get the class of lipids that the given substances belong to
These substances are formed from glycerol and fatty acids
From their make up,we know that they are simple lipids
Thus, the answer here is simple
an avocado can be a simple model of the structure of a cell.
which cell structure is represented by the avocado's skin.
The body of avocado fruit can be compared with the cell structure. The skin of the avocado is relatable with the cell membrane. Thus option B is correct.
What is cell?Cell is the basic unit of life. Cells connect together to forms tissues and tissues forms organs and a group organs forms an organ system. These different organ systems buildup the whole body.
Cell contains the core called nucleus. Inside the nucleus genetic material DNA, ribosomes, Golgi apparatus, lysosomes etc are located. The function of cell membrane is to protect the cell from damages as the skin do for our body.
In plants unlike animals, their cell is protected by a cell wall apart from cell membrane and various other differences are there in the cell structure of plant cells.
The fluid filled portion of cell is called cytoplasm. The inner content of the avocado fruit is comparable with the cytoplasm and its seed can be considered as the model for nucleus.
Therefore, the avocado's skin represents the cell membrane. Hence, option B is correct.
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how many moles of electrons are needed to produce 53.5 mol of Zn(s)
The moles of electrons are needed to produce 53.5 mole of Zn is 107 moles.
What are electrons?Electrons are defined as a subatomic particle having a negative charge that makes up the nucleus of an atom together with protons and neutrons.
The electron has an intrinsic angular momentum of a half-integer number and has a mass that is around 1/1836th that of the proton. The quantum state of any two electrons cannot be identical.
The chemical reaction for solid zinc is
Zn²⁺ + 2e⁻ = Zn (s)
When one mole of zinc ions receive two moles of electrons, one mole of zinc is created.
Electrons equal two moles to form one mole of solid zinc.
The electrons needed to create the 53.5 mole of zinc will provide 2 53.5 = 107 mol.
Thus, the moles of electrons are needed to produce 53.5 mole of Zn is 107 moles.
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