Answer:
In advance
middle
lower
Explanation:
These are the safety precautions needed when carrying out duties in the fume hood.
When planning and preparing to work in a fume hood (a locally designed area to reduce exposure to hazardous fumes). It is advisable to make all equipment readily available at your disposal in advance to reduce and minimize the raising and lowering of the hood sash at intervals.
It is also pertinent to understand that working in the middle of the work surface helps to promote the movement of air and keeps the area neat and tidy.
However, if any case where there is a need to get a new tool or equipment during the process of working in a fume hood, it is advisable to lower the sash at that point in time.
A certain substance X condenses at a temperature of 123.3°C . But if a 650. g sample of X's prepared with 24.6 g of urea ((NH2)2 CO) dissolved in it, the sample is found to have a condensation point of 124.3°C instead. Calculate the molal boiling point elevation constant Kb of X.
Answer:
1.6 °C.kg/mol
Explanation:
Step 1: Calculate the molality of urea
We will use the following expression.
m = mass(urea) / molar mass(urea) × kg solvent
m = 24.6 g / 60.06 g/mol × 0.650 kg
m = 0.630 mol/kg
Step 2: Calculate the boiling point elevation of X
The boiling point elevation is a colligative property that can be calculated using the following expression.
ΔTb = 124.3 °C - 123.3 °C = 1.0 °C
Step 3: Calculate the boiling point elevation constant
We will use the following expression.
ΔTb = Kb × m
Kb = ΔTb/m
Kb = 1.0 °C/(0.630 mol/kg) = 1.6 °C.kg/mol
[10 pts]Iron and vanadium both have the BCC crystal structure and V forms a substitutional solid solution in Fe for concentrations up to approximately 20 wt.% V at room temperature. Determine the concentration in weight percent of V that must be added to iron to yield a unit cell edge length of 0.289 nm.
Answer:
The answer is below
Explanation:
The unit cell edge length (a) = 0.298 nm = 0.289 * 10⁻⁷ cm
The unit volume (V) = a³ = (0.289 * 10⁻⁷ cm)³ = 24 * 10⁻²⁴ cm³
There are 2 atoms per cell, hence N = 2. Also, [tex]n_a=avogadro\ constant=6.02*10^{23}\ mol^{-1}[/tex]
[tex]atomic\ weight\ of\ iron(A_f)=55.85,atomic\ weight\ of\ vanadium(A_V)=50.94,[/tex]
[tex]density\ of\ iron(\rho_f)=7.87,density\ of\ vanadium(\rho_v)=6.1.\\\\V=\frac{nA_{av}}{n_a\rho_{av}} \\\\A_{av}=\frac{100}{C_v/A_v+C_f/A_f} \\\\\rho_{av}=\frac{100}{C_v/\rho_v+C_f/\rho_f} \\\\C_v=concentration\ of\ vanadium,C_f=concentration\ of\ iron.\\\\V=\frac{nA_{av}}{n_a\rho_{av}}=\frac{n*\frac{100}{C_v/A_v+C_f/A_f}}{n_a*\frac{100}{C_v/\rho_v+C_f/\rho_f}}\\\\[/tex]
[tex]24*10^{-24}=\frac{2*\frac{100}{C_v/50.94+C_f/55.85}}{6.02*10^{23}*\frac{100}{C_v/6.1+C_f/7.87}}\\\\7.2=\frac{C_v/6.1+C_f/7.87}{C_v/50.94+C_f/55.85}\ \ \ (1) \\\\Also:\\\\C_v+C_f=100\%\ \ \ (2)\\\\\\solving\ equation\ 1\ and\ 2\ simultaneously\ gives:\\\\C_v=10\% \ and\ C_f=90\%\\\\[/tex]
In the Energy and Specific Heat lab, what temperature should be recorded as the final temperature of the water when measuring the food sample?
A. The temperature of the water when the food sample is first lit
B. The temperature of the water when the food sample has finished burning completely.
C. The highest temperature the water reaches as the sample burns
D. The temperature of the water after the food sample ash has been removed
Answer:
B. The temperature of the water when the food sample has finished burning completely.
Explanation:
Heat or thermal energy is a form of energy that transfers from one object to another due to a temperature difference between the objects. The units for heat are joules or calories.
Calorimetry is the measurement of heat energy released or absorbed in a chemical reaction. A calorimeter is used in calorimetry. The calorimeter operates on the Law of Conservation of Energy which states that energy is never created or destroyed but is transformed from one form to another or between objects.
In food calorimetry, the energy released when food is burned is measured by recording the rise in temperature of water in a calorimeter when a given mass of a food sample is burned completely.
Energy can be calculated using the formula: Q = mc ∆T
where Q = the energy in joules or calories, m = the mass in grams, c = specific heat and ∆T = the change in temperature (final temperature - initial temperature).
The temperature of the water when the food sample has finished burning completely is taken as the final temperature of the water. The sample is allowed to smolder for sometime before recording the final water temperature. This is because the water temperature will continue to rise after the flame has gone out.
what are some sources of error associated with electroplating
Answer:
Cold Shuts. Cold shuts are one of the most common defects found in materials sent for electroplating.
Pitting
Sharp Edges
Cleavage Points
Unclean Manufacturing
Loss of Adhesion
Cracking After Plating — Hydrogen Cracking
Dull and Hazy Deposits in Plating.
Explanation:
Ammonium phosphate is an important ingredient in many solid fertilizers. it can be made by reacting aqueous phosphoric acid with liquid ammonia. calculate the moles of ammonium phosphate produced by the reaction of 0.085 mol of ammonia. be sure your answer has a unit symbol, if necessary, and round it to the correct number of significant digits.
Answer:
0.028 mole of ammonium phosphate, (NH₄)₃PO₄.
Explanation:
We'll begin by writing the balanced equation for the reaction. This is illustrated below:
H₃PO₄ + 3NH₃ —> (NH₄)₃PO₄
From the balanced equation above,
3 moles of NH₃ reacted to produce 1 mole of (NH₄)₃PO₄.
Finally, we shall determine the number of mole of (NH₄)₃PO₄ produced by the reaction of 0.085 mole of ammonia, NH₃. This can be obtained as follow:
From the balanced equation above,
3 moles of NH₃ reacted to produce 1 mole of (NH₄)₃PO₄.
Therefore, 0.085 mole of NH₃ will react to produce = (0.085 × 1)/3 = 0.028 mole of (NH₄)₃PO₄.
Thus, 0.028 mole of ammonium phosphate, (NH₄)₃PO₄ were obtained from the reaction.
GRADE 5 SCIENCE MYA-2020-2021
Testosters are testing the choict of light on a radiometer Team 1 finds that blue light makes the radiometer spin slower when a blue light is 35 centimeters (cm) away. To validate Team 1's test results, how must
Text with and that is 20 cm away
Test what that is 45 cm away
Test with a green light that is 40 cm away
Test with the light that is 35 cm away
Answer:
Test it with a blue light that is 45 cm away.
Explanation:
You'll be given 100 points if you answer this question!!!!!!!!!!!!
3.
What do we call materials
that let heat pass through
them easily?
Thermal conductors
Thermal insulators
Transparent
4.
Which of these is a good
thermal conductor?
Plastic
Wood
Steel
5.
Which of these is a good
thermal insulator?
Steel
Iron
Polystyrene
6.
To save on heating bills, do
you think the roof of a
building should be lined with
a thermal conductor
a thermal insulator
nothing
7.
How does heat travel?
From cold things to hotter things
From hot things to colder things
Between things of the same temperature
Answer:conducts ,steel, polystyrene, thermal insulation
Explanation:
Calculate the mass of butane needed to produce 99.0 g of carbon dioxide.
Express your answer to three significant figures and include the appropriate units.
Answer:
32.7 g
Explanation:
Step 1: Write the balanced combustion reaction
C₄H₁₀ + 6.5 O₂ ⇒ 4 CO₂ + 5 H₂O
Step 2: Calculate the moles corresponding to 99.0 g of CO₂
The molar mass of CO₂ is 44.01 g/mol.
99.0 g × 1 mol/44.01 g = 2.25 mol
Step 3: Calculate the moles of C₄H₁₀ needed to produce 2.25 moles of CO₂
The molar ratio of C₄H₁₀ to CO₂ is 1:4. The moles of C₄H₁₀ needed are 1/4 × 2.25 mol = 0.563 mol.
Step 4: Calculate the mass corresponding to 0.563 moles of C₄H₁₀
The molar mass of C₄H₁₀ is 58.12 g/mol.
0.563 mol × 58.12 g/mol = 32.7 g
3. What determines the frequency (color) of photons?
which of these is an example of the climate of a region?
A. Dry
B. Foggy
C. Overcast
D. Sunny
its dry i think
Explanation:
it might be dry
Which statement about Niels Bohr's atomic model is true?
O Higher orbits have lower energies.
O Each orbit has a specific energy level.
O Electrons can exist in any energy level.
O Orbits close to the nucleus have no energy.
Answer:
O Each orbit has a specific energy level.
Explanation:
Neils Bohr put forward his own model of the atom based on the quantum mechanics originally developed by Planck.
He assumed the Rutherford's model and suggested that the extranuclear part consists of electrons in specific spherical orbits around the nucleus.
The orbits/energy level are the permissible through which the electrons can move through.
His concept is based the concept that the electron can move round the nucleus in certain permissible orbitss
Which of the following is a list of the minimum amount of data needed for determining the molar enthalpy of solution of KCl(s) in pure H2O(1) ? (Assume that the KCl(aq) has the same specific heat capacity as pure water and that the initial temperatures of the KCl(s) and the water are the same.)
(A) Mass of KCl(s), initial temperature of the water, and final temperature of the solution
(B) Mass of H20, initial temperature of the water, and final temperature of the solution
(C) Mass of KCl(s), mass of H20, initial temperature of the water, and final temperature of the solution
(D) Mass of KCl(s), mass of H20, initial temperature of the water, final temperature of the solution, and atmospheric pressure
Answer:
(C) Mass of KCl(s), mass of H20, initial temperature of the water, and final temperature of the solution
Explanation:
molar enthalpy of solution of KCl(s) is heat evolved or absorbed when one mole of KCl is dissolved in water to make pure solution . The heat evolved or absorbed can be calculated by the following relation.
Q = msΔt where m is mass of solution or water , s is specific heat and Δt is change in temperature of water .
So data required is mass of water or solution , initial and final temperature of solution , specific heat of water is known .
Now to know molar heat , we require mass of solute or KCl dissolved to know heat heat absorbed or evolved by dissolution of one mole of solute .
The correct option is option C.
To determine the molar enthalpy of the solution of [tex]Kcl(s)[/tex] is pure [tex]H_2O(l)[/tex]
We need to know that the,
grams of [tex]Kcl(s)[/tex] grams of [tex]H_2O[/tex] Initial temperature of [tex]H_2O[/tex] The final temperature of the solution.Learn More:https://brainly.com/question/25758173
BALANCE THIS CHEMICAL EQUATION PLS, help:)
Answer:
4C₈H₄OH + 35O₂ → 32CO₂ + 10H₂O
Explanation:
The unbalanced reaction expression is given as:
C₈H₄OH + O₂ → CO₂ + H₂O
To solve this problem, we use a mathematical approach.
aC₈H₄OH + bO₂ → cCO₂ + dH₂O
Conserving C: 8a = c
H: 5a = 2d
O: a + 2b = 2c + d
Let a = 1, c = 8, d = [tex]\frac{5}{2}[/tex] , b = 35
4C₈H₄OH + 35O₂ → 32CO₂ + 10H₂O
What role do wolves play in the tundra?
Answer:
predator
Explanation:
Wolves, arctic foxes, and snowy owls are predators in the tundra.
Which of the following BEST describes how these elements would be classified?
A.
Element Q is a nonmetal and element R is a nonmetal.
B.
Element Q is a metal and element R is a metalloid.
C.
Element Q is a nonmetal and element R is a noble gas.
D.
Element Q is a metal and element R is a noble gas.
If the flour mixture is then taken and put into the oven for about 20 minutes, it turns into something very tasty. What kind of change has happened now?
Answer:
physical change
Explanation:
i got the same question sorry for the late response but that's the answer good luck
PLS HELLPPPP
Which of the following objects would have the greatest gravitational attraction between them if they were set 3.0 km apart?
A .20kg object and a 200kg object
A 10kg object and a 100kg object
A 30kg object and a 200,000kg object
A 400,000 kg object and a 100,000,000kg object
Answer:
A 400,000 kg object and a 100,000,000kg object
Explanation:
The objects with the most mass between them will have the greatest gravitational attraction.
This is why the last option is the right choice.
The reason for this is based on the Newton's law of universal gravitation which states that:
"the gravitational force of attraction between two bodies is directly proportional to the product of their masses and inversely proportional to the square of the distance between them".
So, the more the mass, the greater the gravitational attraction between two bodies.
How many moles of hydrogen react with 4.5 moles of oxygen to synthesize water?
Answer:
9moles of hydrogen gas
Explanation:
To solve this problem, we write the reaction expression first;
2H₂ + O₂ → 2H₂O
We have been given the number of moles of oxygen gas to be:
Number of moles of oxygen gas = 4.5moles
From the balanced reaction expression:
1 mole of oxygen gas reacts with 2 moles of hydrogen gas
4.5moles of oxygen gas will react with 4.5 x 2 = 9moles of hydrogen gas
Suppose two students grab an end of a rope. Both shake a rope once in a upward direction to create crests traveling at each other. What would you see when crests meet? What type of interference does this show?
Answer:
This creates destructive interference.
Explanation:
When the two ends meet they will cancel each other out.
Both students are shaking the rope in the upward direction. Hence their crest will meet up and form the constructive interference pattern. The intensity of the increases.
What is constructive interference ?When two waves moves in phase, their crest or troughs add up and the amplitude of the wave increases. This phenomenon is called constructive interference.
If the two waves are passing out of phase to each other then they undergo destructive interference. The amplitude of the destructive interference pattern reduces from their initial values.
Here, both students are shaking the rope in the upward direction. Thus, they are in moving in phase. Hence their crest will meet up and form the constructive interference pattern. The intensity of the increases.
Find more on interference?
https://brainly.com/question/16098226
#SPJ5
Which of the following contains a polyatomic ion?
sodium iodide
carbon monoxide
Iron II oxide
ammonium chloride
Answer:
i think its oxide not too sure
Answer:
Its should be ammonium chloride.
A picture to help you with another question like this
Why do organisms eat food? Be sure to explain your answer.
Answer:
Organisms need to take food to get energy and perform life processes. A living organism undergoes many life processes like nutrition, respiration, digestion, transportation, excretion, circulation of blood, and reproduction. To perform all these life processes the organism needs energy and nutrients.
Explanation:
nnastarannnn his idea
Bond length is the distance between the centers of two bonded atoms. On the potential energy curve, the bond length is the internuclear distance between the two atoms when the potential energy of the system reaches its lowest value. Consider that the atomic radius (sometimes called the covalent or bonding atomic radius) of an element is defined as one-half the distance between the bonded atoms in a homonuclear diatomic molecule. Actual bond lengths in molecules are determined experimentally by such methods as X-ray diffraction and microwave spectroscopy. However, these atomic radii values can be used to give an estimate of the upper limit of bond length in other (heteronuclear) molecules. Given that the atomic radii of H and Br are 37.0 pm and 115 pm , respectively, predict the upper limit of the bond length of the HBr molecule.
Answer:
152 pm
Explanation:
According to the question, we can estimate the bond length from the given values of the atomic radii. This now is the upper limit of the bond length for the molecule.
Since we have that;
Atomic radius of H= 37.0 pm
Atomic radius of Br = 115.0 pm
Bond length = Atomic radius of H + Atomic radius of Br
Bond length = 37.0 pm + 115.0 pm
Bond length = 152 pm
helpppp nowwww plssss!!!
Answer: B
Explanation:
WORTH 40 POINTS HELLPPPP
What class of element is Astatine (At)?
Answer:
halogen.
nonmetal.
Explanation:
PLZ HELP ASAP WILL GIVE BRAINLIST
2AlCl3 + 2Al + 3Cl2
If 20.0 g of aluminum chloride are decomposed, how many molecules of chlorine gas are produced?
A )6.63 x 1022 molecules CI
B )2.70 x 1023 molecules Cl2
C )1.35 x 1023 molecules Cl2
D )9.42 x 1023 molecules Cl2
Explanation:
Molar mass of AlCl3 = 133.34g/mol
Moles of AlCl3 used
= 20.0g / (133.34g/mol) = 0.150mol
Mole Ratio of AlCl3 to Cl2 = 2 : 3,
Moles of Cl2 produced
= 0.150mol * (3/2) = 0.225mol
We know that 1 mole of any gas has
6.023 * 10²³ molecules.
Hence, number of molecules in Cl2
= 0.225mol * (6.023 * 10²³/mol)
= 1.35 * 10²³ molecules. (C)
100 POINTS FOR BEST ANSWER! What is the difference between LDOF and SDOF
An SDOF system is one whose motion is governed by a single, second-order differential equation. Only two variables, position and velocity are needed to describe the trajectory of the system. Many structures can be idealized as single degree-of-freedom systems.
The LDAP Data Interchange Format is a standard plain text data interchange format for representing LDAP directory content and update requests. LDIF conveys directory content as a set of records, one record for each object.
Which statement is always true about conversation of matter?
The mass of a system does not change during a chemical reaction
If a solid forms the mass of a system increases
If a gas forms the mass of a system decreases
The mass of a system changes when a substance changes from liquid to gas, but it does not change in a chemical reaction
Answer:
The mass of a system does not change during a chemical reaction
Explanation:
Correct Answers
PLEASE HELP BRAINLIEST AND 15 points.
1. Which substance is nonvolatile ?
(1.5 Points)
Substance B, boiling point of 105 °C
Substance C, boiling point of 25 °C
Substance A, boiling point of 75 °C
Substance d, boiling point of 45 °C
Answer:
Substance B, boiling point of 105 °C
Explanation:
Non volatile substances have high boiling points
To solve the ultraviolet catastrophe, Planck applied quantization to: Select the correct answer below:
A. vibrational energies of atoms
B. orbital energies of electrons
C. kinetic energies of photons
D. temperature of the system
Answer:
Vibrational energies of atoms
Explanation:
Planck applied quantization to Vibrational energies of atoms because in Black body spectrum prediction a blackbody at equilibrium is expected to radiate energies at various Frequencies ( i.e. increase in radiated energy ∝ increase in frequency ) but towards the ultraviolet region of the spectrum the energy radiated begins to drop as frequency increases. The phenomenon of drop in energy with increase in frequency is termed Ultraviolet catastrophe. hence to solve this phenomenon Planck applied quantization to Vibrational energies of atoms
identified the nucleus that is found in an item that has a stable valance electron configuration
Answer:
Nucleus 3 i believe
