Answer:
just until it covers the sample
a low setting and increasing gradually
pipet
as little solvent as possible
Explanation:
In order to dissolve a chemical sample in a recrystallization solvent, add the room-temperature solvent just until it covers the sample in an Erlenmeyer flask on a hot plate. Turn on the heat, starting at a low setting and increasing gradually. Using a pipet, add additional solvent from a second container on the heat source. Swirl the sample flask after each addition, and try to add as little solvent as possible in order to dissolve the solid.
The eye can see colors because:
a. the cones in the retina send signals to the brain.
b. the rods in the cornea send signals to the brain.
c. the optic nerve determines the color of the object and sends signals to the brain
d. None of the choices are correct.
Answer:
The answer is A, I think.
Answer:
the answer is A
Explanation:
The human eye and brain together translate light into color. Light receptors within the eye transmit messages to the brain, which produces the familiar sensations of color. Newton observed that color is not inherent in objects. Rather, the surface of an object reflects some colors and absorbs all the others.
Beryllium oxide, Beo, is an electrical insulator. How
many moles of beryllium oxide qre in a 250 gram
sample of the compound?
Answer:
There are 10.0 moles of beryllium oxide in a 250 grams sample of the compound.
Explanation:
We can calculate the number of moles (η) of BeO as follows:
[tex] \eta = \frac{m}{M} [/tex]
Where:
m: is the mass = 250 g
M: is the molar mass = 25.0116 g/mol
Hence, the number of moles is:
[tex] \eta = \frac{250 g}{25.0116 g/mol} = 10.0 moles [/tex]
Therefore, there are 10.0 moles of beryllium oxide in a 250 grams sample of the compound.
I hope it helps you!
A sample of a compound was found that has 40.25g of (C) Carbon and 59.75g of (O) Oxygen.
What is the empirical formula for this sample.
Answer:
CO
Explanation:
From the question given above, the following data were obtained:
Mass of Carbon (C) = 40.25 g
Mass of oxygen (O) = 59.75 g
Empirical formula =?
The empirical formula of the compound can be obtained as follow:
C = 40.25 g
O = 59.75 g
Divide by their molar mass
C = 40.25 / 12 = 3.354
O = 59.75 / 16 = 3.734
Divide by the smallest
C = 3.354 / 3.354 = 1
O = 3.734 / 3.354 = 1
The empirical formula of the compound is CO
What type is hydropower?
Answer:
Hydroelectric energy, also called hydroelectricity or hydropower, is a form of energy that uses the power of flowing water to generate electricity. There are three main types of hydroelectric energy: impoundment, diversion, and pumped storage.
Explanation:
A: A 21.3−g sample of dinitrogen monoxide is confined in a 5.76−L vessel. What is the pressure (in atm) at 111°C?
B: Find the density of Freon−11 (CFCl3) at 157°C and 4.65 atm.
g/L = ?
Answer:
A. 2.65 atm.
B. 18.11 g/L.
Explanation:
A. Determination of the pressure
Mass of N₂O = 21.3 g
Volume = 5.76 L
Temperature (T) = 111 °C
Pressure (P) =.?
First, we shall determine the number of mole in 21.3 g of dinitrogen monoxide, N₂O. This can be obtained as follow:
Mass of N₂O = 21.3 g
Molar mass of N₂O = (14×2) + 16
= 28 + 16
= 44 g/mol
Mole of N₂O =?
Mole = mass /Molar mass
Mole of N₂O = 21.3/44
Mole of N₂O = 0.484 mole
Next, we shall convert 111°C to Kelvin temperature. This can be obtained as follow:
T(K) = T(°C) + 273
Temperature (T) = 111 °C
Temperature (T) = 111 °C + 273
Temperature (T) = 384 K
Finally, we shall determine the pressure. This can be obtained as follow:
Number mole of N₂O = 0.484 mole
Volume = 5.76 L
Temperature (T) = 384 K
Gas constant (R) = 0.0821 atm.L/Kmol
Pressure (P) =.?
PV = nRT
P × 5.76 = 0.484 × 0.0821 × 384
Divide both side by 5.76
P = (0.484 × 0.0821 × 384) / 5.76
P = 2.65 atm
B. Determination of the density of CFCl₃
Temperature (T) = 157°C
Pressure (P) = 4.65 atm.
Density of CFCl₃ =?
First, we shall determine the molar mass of CFCl₃. This can be obtained as follow:
Molar mass of CFCl₃ = 12 + 19 + (35.5×3)
= 12 + 19 + 106.5
= 137.5 g/mol
Next, we shall convert 157°C to Kelvin temperature. This can be obtained as follow:
T(K) = T(°C) + 273
Temperature (T) = 157 °C
Temperature (T) = 157 °C + 273
Temperature (T) = 430 K
Finally, we shall determine the density of CFCl₃. This can be obtained as follow:
Temperature (T) = 430 K
Pressure (P) = 4.65 atm.
Molar mass of CFCl₃ (M) = 137.5 g/mol
Gas constant (R) = 0.0821 atm.L/Kmol
Density (D) of CFCl₃ =?
D = PM / RT
D = (4.65 × 137.5) / (0.0821 × 430)
D = 18.11 g/L
Why does there appear to be another duck head in the water?
A
The water in the pond reflects light from the Sun, making a mirror image
B
The molecules in the atmosphere refract the light, splitting it into two ima
С
The duck scatters the light, making hundreds of tiny refractions that collec
D
The bottom of the pond absorbs the light, then projects it toward the surfa
Answer:
it's A. The water in the pond reflects light from the Sun, making a mirror image
Explanation:
i just took the test
what is the mass in grams of 0.687 moles of NH three
A taco from a fast food restaurant contains 7.0 g of fat, 25. g of carbohydrate, and 11 g of protein. How many kJ of energy does the cheeseburger contain? (The caloric values for foods are 38 kJ/g for fat, for carbohydrate, and 17 kJ/g for protein.)
Answer: 878 kJ of energy is there in cheeseburger
Explanation:
Given : calorific value of fat = 38kJ/g
calorific value of carbohydrate = 17 kJ/g
calorific value of protein = 17kJ/g
1 g of fat contains energy = 38 kJ
7.0 g of fat contains energy = [tex]\frac{38}{1}\times 7.0=266 kJ[/tex]
1 g of carbohydrate contains energy = 17 kJ
25 g of fat contains energy = [tex]\frac{17}{1}\times 25=425kJ[/tex]
1 g of protein contains energy = 17 kJ
11 g of protein contains energy = [tex]\frac{17}{1}\times 11=187kJ[/tex]
Total energy = (266+425+187) kJ = 878 kJ
Can someone help me please
Answer:
the answers are a, f, g
and lastly e because they all describe a liquid
Can someone help me with these two?
Answer:
adding
opposite
Explanation:
dont blame me if u get them wrong
Answer:
first one is adding i belive and second one is opposite
Explanation:
5.6 g of an organic compound on burning with excess
of oxygen gave 17.6 g of CO2, and 7.2 g of H,O. The
organic compound is :
Answer:organic compound is : C₄H₈
Explanation: The equation of the reaction of the organic compound burning with excess oxygen gives us the general equation as
C xHy + 1/2(x+ y/2 )O₂ → xCO₂ + y/2H₂O
We first find the number of moles of CO₂ and H₂O
Number of moles of CO₂= Mass/ molar mass
= 17.6g/ 44g/mol ( 12+ 16 x2)
=0.4 moles
Number of moles of H₂O= Mass/ molar mass
= 7.2g/ 18g/mol ( 1 X 2+ 16)
=0.4 moles
From the reaction , we can see that
x = 0.4
and [tex]\frac{y}{2}[/tex]= 0.4 such that y= 0.4 x 2= 0.8
Their ratios become
[tex]\frac{x}{y}[/tex] =[tex]\frac{0.4}{0.8}[/tex]= [tex]\frac{4}{8}[/tex]
Therefor the organic compound CxHy = C₄H₈
Which process breaks down sugars to release energy that powers bodily functions?
Answer:
Cellular respiration
Explanation:
What happens if excess carbon dioxide is not removed from the atmosphere?
A) a decrease in the amount of fossil fuels availabe
B) it may lead to global warming
C) more dead plants and animals not decomposing before getting buried
D) increase in the amount of fossils fuels available
please help fast I need to bring my grade up I'll give 30 points.
Answer:
Carbon dioxide becomes a poisonous gas when there is too much of it in the air you breathe. Besides the effects it can have on the planet and the atmosphere, carbon dioxide poisoning can lead to central nervous system damage and respiratory deterioration in humans and other breathing creatures.
Answer:
Carbon dioxide becomes a poisonous gas when there is too much of it in the air you breathe. Besides the effects it can have on the planet and the atmosphere, carbon dioxide poisoning can lead to central nervous system damage and respiratory deterioration in humans and other breathing creatures.
Explanation:
Hope This Helps! [ :
Arrange the liquids pentane (CH3CH2CH2CH2CH3), pentanol (CH3CH2CH2CH2CH2OH), and pentanal (CH3CH2CH2CH2CHO) in order of decreasing viscosity, surface tension, and boiling point.
Rank from highest to lowest viscosity, surface tension, and boiling point.
Answer:
Following are decreasing order to this question:
Explanation:
Viscosity and surface tension both are inter-molecular by nature (IMFs)
The pentane becomes non-polar and just not H-bondable, so LDF alone would be likely (London Dispersion Force)
Pentanal, but H-bond => is impossible (Dipole-Dipole)
Pentanol is also an OH group, so H-bond => is probable (Hydrogen Bonding)
Higher air tension and viscosity than higher IMFs (because the atoms of fluids are more drawn). To lower the IMF (and therefore the viscosity/surface stress decreases)
pentanol
pentanal
pentane
How can weak acids and weak bases cause pH stress to cells?
a. Weak bases will only cause pH stress at low pH.
b. If a cell has transporters that are not well regulated, weak acids or weak bases can accumulate inside the cells and cause stress.
c. Only weak acids can cause stress by diffusing across a membrane at low pH.
d. At certain pH levels, both weak acids or weak bases will be uncharged, and thus are small uncharged molecules that can diffuse across a membrane and cause pH stress inside the cell. e. Weak acids and weak bases do not cause stress.
Answer:
b
Explanation:
If a cell has transporters that are not well regulated, weak acids or weak bases can accumulate inside the cells and cause stress.
molecular formula of CH3-CH2-CH2-CH2-CH2-Cl
Answer:
C₅H₁₁Cl
Explanation:
Count all the carbon, hydrogen, and chlorine atoms. The number of atoms of each element is the subscript for each element in the formula. No subscript is understood to be one. Carbon goes first, hydrogen goes second, and chlorine goes last when writing the formula.
Is this the correct formula for magnesium acetate? Mg(C2H3O)2
Answer:
no
Explanation:
magnesium acetate= Mg(C2H3O2)2
Decide whether a chemical reaction happens in either of the following situations. If a reaction does happen, write the chemical equation for it. Be sure your chemical equation is balanced and has physical state symbols. situation chemical reaction.
A strip of solid tin metal is put into a beaker of 0.074M MgBr2 solution .
Answer:
Sn(s) + MgBr2(aq) --> SnBr2(aq) + Mg(s)
Explanation:
Decide whether a chemical reaction happens in either of the following situations.
- A reaction happens. The type of this reaction is the single replacement reaction.
If a reaction does happen, write the chemical equation for it.
Sn(s) + MgBr2(aq) --> SnBr2(aq) + Mg(s)
What is full ground state electron configuration of C-?
Answer:
[tex]1s^{2}[/tex] [tex]2s^{2}[/tex] [tex]2p^{2}[/tex]
Explanation:
Simply [tex]1s^{2}[/tex] [tex]2s^{2}[/tex] [tex]2p^{2}[/tex]
Coal has two valent electrons, so there is 2 in 2p orbital
MQ : Which parts of the brain had most likely been affected?
Answer:
the cerebrum
Explanation:
answer is A
The foam football Coach Johnson left in his chair will stay there until he
moves it to sit in the chair.
A. Newton’s first law
B. Newton’s second law
C. Newton’s third law
Answer:
B. Newton’s second law
Explanation:
correct me if im wrong
Answer:
Its c newton third law
Explanation:
His third law states that for every action (force) in nature there is an equal and opposite reaction. In other words, if object A exerts a force on object B, then object B also exerts an equal and opposite force on object A. Notice that the forces are exerted on different objects.
Would you expect a reaction to occur with Hydrogen gas and Copper (II) chloride?
The copper itself can react with hydrogen
Here is the chemical reaction
2CuCl2(aq) + H2(g) -> 2CuCl(s) + 2HCl(g)
the amount of copper sulphate used in dissolution is
Answer:
80 gm/mol
Explanation:
it may be helpful
Why does Hydrogen not belong to any group?
Answer: Hydrogen is not in any group because it only has on electron
Explanation:
structure of 2,6-diiodo-4-methyl-5-propylheptane
Explanation:
2,6-Dibromo-4-isopropylphenol
2432-16-8
2,6-dibromo-4-propan-2-ylphenol
Phenol, 2,6-dibromo-4-(1-methylethyl)-
4-isopropyl-2,6-dibromophenol
Farsighted people have trouble seeing objects that are close to their eyes.
True
False
In this stage of team building, the team is running smoothly and they are comfortable in their roles.
norming
performing
forming
storming
Answer:
performing
Explanation:
At STP, in the equation C(g) + O2(g) --> CO2(g), one liter of O2 yields how many liters of CO2?
Answer:
3 I think but ask someone else too
A tank contains one hundred fifty kmol of an aqueous phosphoric acid solution with 5.00 mole% H3PO4. The solution is concentrated by adding pure phosphoric acid at a rate of 30.0 L/min. Molecular weight of phosphoric acid is 98. Density of phosphoric acid is 1.834 kg/L. Determine the mole fraction of phosphoric acid in the tank at 25 minutes.
Answer:
Mole fraction = 0.1313
Explanation:
given data
Addition rate of pure phosphoric acid = 30L/min
Phosphoric acid added in 25 min = 750 L
solution
mass is express as here
mass = density × volume and number of moles = mass ÷ molar mass
So, In terms of moles
phosphoric acid added = (750 × 1.834) ÷ 98
phosphoric acid added = 14.036 kmol
and
moles of phosphoric acid in tank = 0.05 × 150 + 14.036
moles of phosphoric acid in tank = 21.536 kmol
and
Moles of water in tank = 0.95 × 150
Moles of water in tank = 142.5 kmol
So that Mole fraction of phosphoric acid in tank
Mole fraction = 21.536 ÷ (21.536+142.5)
Mole fraction = 0.1313
What is the primary function of the chromosome?
Answer:
Store the genetic instructions needed to specify traits.
In DNA, the primary function of chromosome is store the genetic instructions needed to specify traits.
What is DNA?
DNA is a hereditary material which is present in human beings as well as all other living organisms. Every cell which is present in an organism's body has DNA which is the same. Most of the DNA is situated in the cell's nucleus and small amount of it can be found in the cell's mitochondria as well.
Information which is stored in DNA is stored as codes made up of four chemical bases namely, adenine, thymine , cytosine and guanine.Human DNA consists of 3 billion bases .The order of the bases determines information which is required for building and maintaining an organism.
DNA bases are capable of pairing up with each other. Adenine pairs with thymine and guanine pairs up with cytosine .Each base is also attached to a sugar molecule and a phosphate group. A base, phosphate sugar are together called as nucleotides.
Learn more about DNA,here:
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