Answer: Lavoisier organized a list of the known elements of his day as four categories. Newlands was the first to organize the elements and show that properties repeated in a periodic way. Mendeleev and Meyer proposed periodic tables showing a relationship between atomic mass and elemental properties. Moseley organized the elements by atomic number instead of atomic mass.
Explanation:
why do we need digital technology in school?
Answer: See explanation
Explanation:
Digital technologies refers to the electronic tools, or devices that can be used to generate data, store them or process data. e.g. mobile phones, ebooks etc.
Digital learning makes use of technology. Effective use of digital learning tools can help increase the engagement of students. This csn.aksi be used by the teachers to enhance personalized learning and also improve the lesson plans.
Digital technology can enhance collaboration, and communication with the students. The use of videos, robots, virtual classrooms, augmented reality and other technologies can bring about fun and foster inquisitiveness.
A 72.0 g sample of an organic solid is dissolved in 180mL of water. The solid is extracted using one 60 mL extraction in the first extraction of an organic solvent which has a partition (distribution) coefficient with water of 10. The first extraction removed 55.4 g of solid from water. What are the numbers that need to go in box A and B to calculate the volume of solvent (y) that would be necessary to remove an additional 7.0g from the remaining sample dissolved in water. You DON'T have to complete the calculation to solve for y.
Answer:
[tex]V_{7.0}\approx 235ml[/tex]
Explanation:
From the question we are told that
mass of sample [tex]M=72.0 grams[/tex]
volume of water [tex]V=180 mL[/tex]
volume for extraction [tex]V'=60mL[/tex]
partition (distribution) coefficient water [tex]d=10[/tex]
initial extraction removal [tex]x=55.4g[/tex]
Generally the equation for the weight of sample [tex]x_n[/tex] is mathematically given by
[tex]x_n=x*(\frac{DV}{DV+V'})^n[/tex]
[tex]x_n=55.4(\frac{10*180}{10*180+60})^1[/tex]
[tex]x_n=53.613g[/tex]
Generally the weight extracted [tex]x_e[/tex] is therefore
[tex]w_e=x-x_n[/tex]
[tex]w_e=55.4-53613[/tex]
[tex]w_e=1.787[/tex]
[tex]w_e=1.787[/tex] is extracted with 60ml solvent .
Therefore volume of solvent (y) that would be necessary to remove an additional 7.0g
[tex]V_{7.0}=\frac{60}{1.767}*7[/tex]
[tex]V_{7.0}=235.030ml[/tex]
[tex]V_{7.0}\approx 235ml[/tex]
Do nitrates always form precipitates?
Answer:
Nitrates compared to sulphates are much more soluble therefore won't form precipitates easily.
14. If one half-life is the amount of time it takes for a radioactive isotope to decay by a factor of 2,
approximately which percent describes how much of the initial quantity of a substance would
remain after 2.3 half-lives?
Answer:
Since the equation for amount remaining is (1/2)^n, where n stand for the number of half lives, after 2.3 half lives the equation is (1/2)^2.3. This makes the answer about 1/4.92, which converts to about 20% of the original amount.
Explanation:
Since the equation for amount remaining is (1/2)^n, where n stand for the number of half lives, after 2.3 half lives the equation is (1/2)^2.3. This makes the answer about 1/4.92, which converts to about 20% of the original amount.
Calculate the ratio of the effusion ratesbetween chlorine gas (Cl2, molar mass = 71 g/mol) and iodine gas(I2, molar mass = 254 g/mol).
a)0.280
b)1.89
c)3.58
d)8.43
Answer:
d is the correct answer
Explanation:
A piece of unknown solid substance weighs 437.2 g, and requires 8460 J to increase its temperature from 19.3 °C to 68.9 °C.What is the specific heat of the substance?
Answer:
0.3832
Explanation:
Givens
m = 437.2 grams
c = ?
delta t = 69.8 - 19.3
H = 8460 J
Formula
H = m*c*Δt
Solution
8460 = 437.2 * c * (69.8 - 19.3)
8460 = 437.2 * c * 50.5
8460 = 22078.6 * c
c = 8460 / 22078,6
c = .3832 J / (oC * gr)
You have to decide to change the temperature at which you run a certain reaction in hope of obtaining more product more quickly. You find that you actually get less of the desired product, although you get to the equilibrium state more quickly. Explain what happened.
Answer:
see explanation
Explanation:
The reaction has a negative rate law; i.e., Rate = - ΔConcentration / ΔTime which is graphically a negative slope for the plot of Rate as a function of reactant concentration. => Rate ∝ f(Reactant Concentration). However, by raising the temperature, an increase the probability of reaction occurs and the formation of more product.
If 8.25g N2 gas is inside a 1.50L flask at 325K what is the pressure inside the flask
Answer:
8.26g
Explanation:
8.25g +1.50÷325k=8.26g
Pleaseee helpppp!!!!!!!!
Answer:
a covalent would be the two that are nonmetals
Can tell the answer pls
Explanation: where the article????
Bacteria can be heterotrophs or autotrophs
true or false?
Answer:
True
Explanation:
I learned about it a few years ago
For many years chloroform (CHCl3) was used as an inhalation anesthetic in spite of the fact that it is also a toxic substance that may cause severe liver, kidney, and heart damage. Calculate the percent composition by mass of this compound to four significant figures.
Answer:
SEE EXPLANATION
Explanation:
We must first obtain the molar mass of CHCl3 as follows;
CHCl3 = ( 12.01 * 1 )+ (1.008 * 1 ) + ( 35.45 * 3 ) => 119.37 g/mol
Then we obtain the percentage by mass of each element
For Carbon = ( atomic mass C / molar mass CHCl3 ) * 100
C = (12.01 / 119.37 ) * 100
C = ( 0.1006 * 100 )
C = 10.06 %
For Hydrogen :
H = ( atomic mass H / molar mass CHCl3 ) * 100
H = ( 1.008 / 119.37 ) * 100
H = 0.008444 * 100
H = 0.8444 %
For Chlorine :
Cl ( molar mass Cl3 / molar mass CHCl3 ):
Cl = ( 3 * 35.5 / 119.37 ) * 100
Cl = ( 106.5 / 119.37 ) * 100
Cl = 0.8921 * 100
Cl = 89.92%
No changes will ever be made to the scientific classification system. Is this a valid statement? Why or why not? HELP PLZ GIVING BRANLIESTTT
Answer:
No.
Explanation:
Since classification, is a system of categorizing living things new discoveries; animals are discovered everyday. There are some we didn't discover yet, so the scientists are going to have to make another one for the future.
No changes will ever be made to the scientific classification system. This is not a valid statement.
What is scientific classification?Biological Classification is the way scientists use to categorize and organize all of life. It can help to distinguish how similar or different living organisms are to each other
Millions of plants, animals, and microorganisms found on earth, have been identified by the scientists while many new species are still being discovered around the world.
Thus, to classify these newly discovered species, with new characters, new systems of classification have to be devised every now and then.
Therefore, No changes will ever be made to the scientific classification system. This is not a valid statement.
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fossil fuels form in sedimentary rocks when-
Answer:
fossil fuels form in sedimentary rocks when increased heat and pressure applies to fossils.
Explanation:
fossil fuels are made when sedimentary rock gets heat and pressure increased.
25 ml of liquid and has a mass of 19 grams. Calculate the density.
Which of these compounds are molecular?
CBr4
FeS
P4O6
PbF2
Answer:
I think it's answer is P4O6
I hope it's helpful for you...
A solution is made by dissolving 62.42 g of ammonium sulfate in enough
water to make 50.0 mL of solution. What is the molarity of this solution?
(**Use only numerical answers with 3 significant figures. The units are given
in the question.)
Answer:
9.46 M
Explanation:
Molarity is a measure of the molar concentration of a solution. It can be calculated by the following formula
Molarity = number of moles/volume
Using moles = mass/molar mass
Molar Mass of Ammonium sulfate (NH₄)₂SO₄ =
{14 + 1(4)}2 + 32 + 16(4)
= {14 + 4}2 + 32 + 64
= 18(2) + 96
= 36 + 96
= 132g/mol
mole = mass/molar mass
mole = 62.42 ÷ 132
mole = 0.473mol
- Molarity = mole ÷ volume
Volume = 50.0 mL = 50/1000 = 0.05 L
Molarity = 0.473 ÷ 0.05
Molarity = 9.46 M
2.85 x 10-3 moles of an unknown compound has a mass of 0.206 g. The compound could be:
Answer:
Calcium sulfide (CaS)
Explanation:
From the question
Number of mole (n) = reacting mass (R)/molar mass (m)
n = R/m.................... Equation 1
make m the subject of the equation
m = R/n...................... Equation 2
Given: R = 0.206, n = 0.00285 moles.
Substitute these values into equation 2
m = 0.206/(0.00285)
m = 72.3 g/mol
From the above, the compond with molar mass close to 72.3 g/mol is Calcium sulfide (CaS)
An arrow is fired at a target on a high wall. How does the energy change between the moment the arrow is fired and
Che moment it hits the target?
O The potential energy and kinetic energy remain the same.
O The potential energy decreases as kinetic energy increases.
O The kinetic energy decreases as potential energy increases.
O The kinetic energy remains at zero, but potential energy increases.
Answer:
C brainliest
Explanation:
An arrow is fired at a target on a high wall. The kinetic energy will decrease as potential energy increase.
Kinetic energy is one of the energies that is related to the motion of the particle and potential energy is one of the energies that is related to the position and height of the particle.
As the arrow in the question will go high to the wall, speed of arrow will keep on decreasing and kinetic energy keeps on decreasing and as height increases potential energy also increases.
We know that As per law of conservation of energy, as kinetic energy decreases potential energy will increase in the same amount.
Therefore, An arrow is fired at a target on a high wall. The kinetic energy will decrease as potential energy increase.
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What do concentric contour lines on a topographic map represent?
Answer:
Concentric circles of contour lines indicate a hilltop; concentric circles with hachure marks indicate a close depression.
Explanation:
Hope this helped Mark BRAINLIEST!!!
define the term semiconductor and give an example of a metalloid
Answer:
A metalloid is a chemical element that exhibits some properties of metals and some of nonmetals.The closer you get to the zone, the more blurred the properties become. Metalloids tend to be semiconductors; silicon is the best known example of a semiconductor. Most microchips and microprocessors are made with silicon.
Explanation:
That is what i know on the answer
To solve this we must be knowing each and every concept related to metalloid. Therefore, in above given ways semiconductor can be defined.
What is metalloid?Metalloids are chemical elements with physical and chemical characteristics that fall between between metal and nonmetal.
A metalloid is indeed a chemical element with characteristics of both metals and nonmetals. The properties grow increasingly blurred as you move closer to the zone. The seven most well-known metalloids are boron, germanium, silicon, antimony, arsenic, tellurium, and polonium.
Metalloids are often semiconductors, with silicon being the most well-known example. Silicon is used to make the majority of microchips and microprocessors.
Therefore, in above given ways semiconductor can be defined.
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Reaction of HBr with 3-methylcyclohexene yields a mixture of four products cis-and trans-1-bromo-3-methylcyclohexane and cis-and trans-1-bromo-2-methylcyclohexane. The analogous reaction of HBr with 3-bromocyclohexene yields trans-1,2-dibromocyclohexane as the soul product.
Required:
Draw structures of the possible intermediates and mechanismfor the latter reaction.
Answer:
See explanation
Explanation:
The mechanism of this reaction including intermediates are shown in the image attached to this answer.
The reaction of HBr with 3-bromocyclohexene yields trans-1,2-dibromocyclohexane as the sole product because; the proton first attacks the 3-bromocyclohexene and a brominium ion is formed. This brominium ion is a cyclic intermediate as shown in the image attached.
Attack of a bromine ion afterwards must lead to the formation of trans-1,2-dibromocyclohexane as shown.
Sodium acetate never precipitates
True or False?
Answer:
it is false Sodium acetate NEVER precipitates
Answer:
It is indeed true, Sodium acetate never precipitates
which behavior is a innate adaptation a.hunting in packs b.fighting for portection .c mating d. all behaviors are innate
Answer:
c. mating
Explanation:
What is the speed of sound in dry air at 20°C?
For the chemical reaction 2KI+Pb(NO3)2⟶PbI2+2KNO3 how many moles of lead(II) iodide (PbI2) are produced from 8.0 mol of potassium iodide (KI)? number of moles: mol
Answer:
the number of moles is 6
Explanation:
The computation of the number of moles is given below:
According to the question
Since 2 mol of KI produces 1 mol of PbI2
based on the above information
The number of moles would be
8 mol will produce 6 mol of PbI2
Therefore the number of moles is 6
Hence, the same is considered and relevant too
The other things would be ingored
Estimate the solubility of barium fluoride, BaF2, in a 0.100 M solution of barium nitrate, Ba(NO3)2, given that the K sp of BaF2 is 2.45×10-5.
A)7.83×10-3 M
B)1.57×10-2 M
C)7.83×10-4 M
D)2.45×10-4 M
Answer:
A) 7.83 x 10^-3 M
Explanation:
7.83 x 10⁻³ M is the solubility of barium fluoride, BaF[tex]_2[/tex], in a 0.100 M solution of barium nitrate, Ba(NO[tex]_3[/tex])[tex]_2[/tex], given that the K sp of BaF[tex]_2[/tex]is 2.45×10-5. The correct option is option A.
What is solubility?The ability of a material, the solute, to combine with some other substance, the solvent, is known as solubility in chemistry. Insolubility, or the solute's inability to create such a solution, is the opposite attribute. The concentration of a solute inside a saturated solution is typically used to determine how much of a substance is soluble in a certain solvent.
The two compounds are said to be just at solubility equilibrium at this time. There might not be a limit for some solutes or solvents, in which case they two are referred to as "miscible in any quantities." Whereas the solvent is often solid or liquid, the solute may be either a solid, liquid, or gas.
BaF[tex]_2[/tex]=0.100 M
Ba(NO[tex]_3[/tex])[tex]_2[/tex]=0.100 M
K sp of BaF[tex]_2[/tex]=2.45×10⁻⁵
solubility of barium fluoride=2.45×10⁻⁵×0.100 =7.83 x 10⁻³ M
Therefore, the correct option is option A.
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identify the solute in the following: carbon dioxide dissolved in water
a. water
b. carbon dioxide
c. none of the above
d. carbon dioxide and water
Answer:
B
Explanation:
its solute state is gas and dissolve in (solvent) liquid which is water
What is the source of the forces that cause this plate movement
Convection currents in the mantle, I got it right on a p e x
A double-replacement reaction takes place when aqueous Na,co, reacts with aqueous Sn(NO3), according to the following equation. Na,co, + Sn(NO,)
You would expect one of the products of this reaction to be
20
Sn2(CO3)2
NaNO,
O Nas
OCNO,
Answer:
[tex]Sn(CO_3)_2[/tex] and [tex]NaNO_3[/tex].
Explanation:
Hello there!
In this case, according to the described chemical reaction between sodium carbonate and tin nitrate, we can write the undergoing chemical reaction:
[tex]2Na_2CO_3+Sn(NO_3)_4\rightarrow Sn(CO_3)_2+4NaNO_3[/tex]
Thus, we notice that the products are strontium carbonate and sodium nitrate, whose formulas are [tex]Sn(CO_3)_2[/tex] and [tex]NaNO_3[/tex] respectively.
Best regards!