Answer:
Explanation:
Average Atomic mass of any element =[ ∑ Abundance* mass of element] /100
= 10*20 +11*80 /100
= .........
Hope this helps you
For which purpose do biochemist insert human genes into bacteria
Answer: to find a cure for the common cold to produce insulin for diabetics
Explanation: It has helped many people
which substance will form a solution when mixed with liquid benzene (c6h6)
Answer: [tex]I_{2} (l)[/tex]
Explanation: Because C 6 H 6 is nonpolar substance and I 2 is also nonpolar compound
According to the concept of solubility,iodine will form a solution when mixed with liquid benzene as both are non-polar substances.
What is solubility?Solubility is defined as the ability of a substance which is basically solute to form a solution with another substance. There is an extent to which a substance is soluble in a particular solvent. This is generally measured as the concentration of a solute present in a saturated solution.
The solubility mainly depends on the composition of solute and solvent ,its pH and presence of other dissolved substance. It is also dependent on temperature and pressure which is maintained.Concept of solubility is not valid for chemical reactions which are irreversible. The dependency of solubility on various factors is due to interactions between the particles, molecule or ions.
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Which represents the greatest time frame in which a short-term environmental change can occur?
in days
O in minutes
O over hundreds of years
O over thousands of years
Answer:
in days
Explanation:
A short term environmental change refers to changes in the environment that happens within a short period of time, for example, flooding, drought, volcanic eruptions etc. In contrast to short term environmental change, long term environmental change takes place over a long period of time hence species have a longer time to adapt to it. Short term environmental changes may or may not be caused by humans. An example of a short term environmental change caused by humans is oil spillage. Short term environmental changes may lead to the the migration of species from the ecosystem.
Short term environmental changes usually occur within a very short time. The greatest time frame in which a short term environmental change can occur is in a matter of days. Only longterm environmental changes span hundreds and thousands of years.
Answer:
it is c
Explanation:
i took the test :)
WILL MARK BRAINLIEST IF GOOD EXPLANATION...
Ethyl acetate is a sweet-smelling solvent used in varnishes and fingernail polish remover. It is produced industrially by heating acetic acid and ethanol
together in the presence of sulfuric acid, which is added to speed up the
reaction. The ethyl acetate is distilled off as it is formed. The equation for the
process is as follows.
CH3COOH + CH3CH2OH --> CH3COOCH2CH3 + H2O
Determine the percentage yield in the following cases:
a. 68.3 g of ethyl acetate should be produced but only 43.9 g is recovered.
b. 0.0419 mol of ethyl acetate is produced but 0.0722 mol is expected. (Hint:
Percentage yield can also be calculated by dividing the actual yield in moles
by the theoretical yield in moles.)
c. 4.29 mol of ethanol is reacted with excess acetic acid, but only 2.98 mol of
ethyl acetate is produced.
d. A mixture of 0.58 mol ethanol and 0.82 mol acetic acid is reacted and 0.46
mol ethyl acetate is produced. (Hint: What is the limiting reactant?)
Answer:
a) 64.27%
b) 58%
c) ethanol is the limiting reactant
d) ethanol is the limiting reactant
Explanation:
We have to note that the expected yield is the theoretical yield while the actual mass or amount of product formed is the actual yield.
a) theoretical yield=68.3g
Actual yield= 43.9 g
Percentage yield= 43.9/68.3 ×100
Percentage yield= 64.27%
b) theoretical yield= 0.0722 moles
Actual yield = 0.0419
Percentage yield= 0.0419/0.0722 × 100
Percentage yield= 58%
c) note that the limiting reactant yields the least number of moles of product
Ethanol will be the limiting reactant since it is not present in excess.
d) from the reaction equation;
1 mole of acetic acid produces 1 mole of ethyl acetate
0.58 moles of ethanol produces 0.58 moles of ethyl acetate
1 mole of acetic acid yields 1 mole of ethyl acetate
Hence 0.82 moles of acetic acid yields 0.82 moles of ethyl acetate
Hence ethanol is the limiting reactant.
An acid is added to water, and a new equilibrium is established. What is the system after the acid is added? A. pH w = 1 x 10-14 B. pH w -14 C. pH > pOH and Kw = 1 x 10-14 D. pH > pOH and Kw > 1 x 10-14
Answer:
C. pH > pOH; Kw = 1.0 * 10^-14
Explanation:
The ion product of water, Kw = [H+]*[OH-] = 1.0 * 10^-14. It is a constant.
When an acid or base is added to water, its ion product does not change as it a constant. However, the relative concentrations of H+ ions and OH- ions will change depending on whether an acid or base is added to water.
When an acid is added to water, the concentration of H+ ions increases while that of OH- ions decreases, and vice versa.
Therefore, in the above situation where an acid is added to water, pH > pOH; Kw = 1.0 * 10^-14
Calculate the Molarity of a 0.23 mole solution of sucrose, C 12 H 22 O 11 that is dissolved in 5 liters of water.
Answer:
0.046 M
Explanation:
Molarity = mol solute/ L solution = 0.23 mol/ 5 L = 0.046 mol/L = 0.046 M
a sample of a compound that contains only the elements C,H and N is completely burned in O2 to produce 44g of CO2, 45g of H2O, and some NO2. A possible empirical formula of the compound is A. CH2N B.CH5N C.C2H5N D.C3H3N2
Answer:
B. CH₅N
Explanation:
The combustion reaction of a compound CₐHₓNₙ with O₂ is:
CₐHₓNₙ + O₂ → a CO₂ + X/2 H₂O + n NO₂
Where 1 mole of CₐHₓNₙ with an excess of O₂ produce a moles of CO₂, X/2 moles of H₂O and n moles of NO₂
Thus, you need to convert the mass of CO₂ and H₂O to moles to find the C:H ratio and determine a possible empirical formula thus:
Moles CO₂ (Molar mass 44g/mol):
44g ₓ (1mol / 44g) = 1 mole CO₂ = 1 mole C
Mole of H₂O (Molar mass 18g/mol):
45g ₓ (1 mol / 18g) = 2.5 moles H₂O = 5 moles H
Thus, in the compound you have 5 moles of H per mole of C, and a possible empirical formula is:
B. CH₅NThe only structure that meet this C:H ratio
The most likely empirical formula for the one that exemplifies a specimen of the compound containing the element C, H, and N which are completely combusted in oxygen to generate 44g Co2, 45g of H2O, and a little NO2 would be:
B). CH₅N
The reaction of combustion taking place in the compound CₐHₓNₙ using [tex]O_{2}[/tex] (oxygen) would be:
[tex]C_{a} H_{x} N_{n} + O_{2}[/tex] → [tex]aCO_{2} + X/2 H_{2}O + nNO_{2}[/tex]
In this reaction, 1 mole belonging to [tex]C_{a} H_{x} N_{a}[/tex] having additional [tex]O_{2}[/tex] (oxygen) leads to generating '[tex]a[/tex]' moles of [tex]CO_{2}[/tex] (Carbon dioxide), [tex]X/2[/tex] number of moles of [tex]H_{2}O[/tex](Hydrogen), and n amount of moles of Nitrogen([tex]N[/tex]).
Therefore, it will be required to transform the mass of [tex]CO_{2}[/tex] and [tex]H_{2}O[/tex] in the form of moles to deduce the ratio C:H to look for the likely empirical formula.
[tex]CO_{2}[/tex] Moles (∵ Molar mass [tex]= 44g/mol)[/tex]
= [tex]44g[/tex] × [tex](1mol/44g)[/tex]
[tex]= 1 mole[/tex] of [tex]CO_{2}[/tex]
[tex]= 1 mole[/tex] of C
[tex]H_{2}O[/tex] Moles (∵ Molar mass =[tex]18g/mol)[/tex]
[tex]= 45g[/tex] ₓ [tex](1 mol / 18g)[/tex]
[tex]= 2.5 moles[/tex] [tex]H_{2}O[/tex]
[tex]= 5[/tex] [tex]moles of H[/tex] because (H * 2)
∵ The C:H ratio is 1:5 implying that formula would include 5 H moles and 1 C mole. So, CH₅N is the correct option.
Thus, option B is the correct answer.
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Distillation is a _____________ separation technique.
chemical
physical
Answer:
Chemical
Explanation:
Because it's being done by chemical means
Step 3: Measure Solubility in Cold Water
10
0
-10
80
100 m
60
-40
20
Temperature of the water to the nearest degree:
ANSWER IS 2°C. !!!
Answer:
2 degrees celcius
Explanation:
Give two examples of solutions that you might find or prepare in a kitchen.
Explanation:
solid liquid
solid gas
liquid solid
What volume will be occupied by 11.7 g of Helium in a balloon at an altitude of 10.0 km if the air pressure is 0.262 atm and the temperature is -50.0 °C?
Answer: 204 L
Explanation:
According to ideal gas equation:
[tex]PV=nRT[/tex]
P = pressure of gas = 0.262 atm
V = Volume of gas = ?
n = number of moles = [tex]\frac{\text {given mass}}{\text {molar mass}}=\frac{11.7g}{4g/mol}=2.92[/tex]
R = gas constant =[tex]0.0821Latm/Kmol[/tex]
T =temperature =[tex]-50^0C=(273+(-50))K=223K[/tex]
[tex]V=\frac{nRT}{P}[/tex]
[tex]V=\frac{2.92\times 0.0820 L atm/K mol\times 223K}{0.262atm}=204L[/tex]
Thus volume occupied by 11.7 g of Helium in a balloon is 204L
3. Sugar solution(sugar + water) is a homogeneous mixture and sugar can be separated from water through evaporation .Comment.
Plz, answer
Answer:
water is the answer
Explanation:
The sugar and water mix to make sweet water but the sun extracts the sugar from the water leaving only normal water
Answer:
water can be evaporated
Explanation:
the water will be evaporated leaving only the sugar residue behind.
does a periodic table indicate the occurrence of elements
Answer:
no
Explanation:
it only shows the atomic number and basically the chemical behavior of the element
What are the two ways that humans lose heat? PLS help thank you!
Answer:
Evaporation, Radiation
Explanation:
Evaporation of water from your skin if it is wet (sweating). ...
Radiation (similar to heat leaving a woodstove).
Which statement accurately describes the movement of Earth’s plates due to convection currents?
Answer:
Volcanic eruptions.
Element X is a solid that is brittle, lacks luster,and has six valence electrons. In which group on the Periodic Table would element X be found
Answer:
Sulfur?
Explanation:
Sulfur has 6 valence electrons and does not have luster.
What is the molarity of a solution that contains 2 moles of KCl in 4 L of solution? a 2.0 M b 0.5 M c 0.25 M d 8.0 M
Answer:
A.) 2.0 M
Explanation:
Molarity=mole of solutes/Liters of solution so M=mol/L
2moles/4 L =2 M
explain why an indicator is used in titration
Answer:
Titrations. Because a noticeable pH change occurs near the equivalence point of acid-base titrations, an indicator can be used to signal the end of a titration. When selecting an indicator for acid-base titrations, choose an indicator whose pH range falls within the pH change of the reaction.
Hope it helped!!
Name the process that releases carbon dioxide into the atmosphere.
) What is the definition of an enzyme? A.Enzymes are carbohydrate molecules that act as catalysts to speed up chemical reactions in living things. B.Enzymes are polymer molecules that act as catalysts to slow down chemical reactions in living things. C.Enzymes are protein molecules that act as catalysts to speed up chemical reactions in living things. D.Enzymes are fat molecules that act as catalysts to speed up chemical reactions in living things. E.Enzymes are protein molecules that act as catalysts to slow down chemical reactions in living things.
Answer:
option c
enzymes are protein molecules that act as catalysts to speed up bio chemical reactions
For neap tides, what must the angular alignment be between the sun, earth and moon?
Answer:
The angular alignment is 90 degrees
Explanation:
The neap tide is a type of tide which occurs around seven days after a spring tide. This type of tide happens twice every month.
The tide is usually moderate and it exists when the sun and moon are usually at right angles to each other when it occurs. A right angle is also known as 90 degrees which validates the tide occurring at an angle 90.
Which of the following statements is true? Less rain and snow falls in smoky areas than in other areas. Acid rain causes corrision of buildings and statues. The first laws againts pollution were passed in the 1990s. Cars are the leading cause of nitrogen oxide pollution.
Answer:
Acid rain causes corrosion in buildings.
Explanation:
This is true because acid rain over time can eat away at the building.
scientists often work on projects for a long time and fail to see sources of error in their research. Which process allows an outside expert to look at the scientist’s project and point to sources of error?
Answer:
Replication
Explanation:
In science, the work of a scientist is regarded as authentic if other experts in other places can follow the same steps as he/she claimed to follow and arrive at the same result.
For example, a scientist in California, United States of America may carry out a research and publish his findings. Another scientist in Christchurch New Zealand following exactly the same procedure is expected to arrive at the same results as the original researcher if there were no errors in the work.
However, where there are disparities in results, the scientist in Newzealand may discover errors that were unknown to the original researcher in the united States. The New Zealand scientist was carrying out a process known as 'replication'. That is, repeating a scientific research in order to obtain the same results thereby validating the research.
1
Net ionic equations remove spectator ions and shows only the chemical species that are involved in the chemical reaction. Write the net ionic equation for the following acid base reaction.
Molecular Equation: 2 HCl (aq) + Mg(OH)2 (aq) → MgCl2 (aq) + 2 H2O (l)
Complete Ionic: 2 H+ (aq) + 2 Cl– (aq) + Mg2+ (aq) + 2 OH– (aq) → Mg2+ (aq) + 2 Cl– (aq) + 2 H2O (l)
Net Ionic Equation: ______________________________________________________
Answer:
The reaction of an acid and a base is called a neutralization reaction. ... However, in the reaction between HCl(aq) and Mg(OH) 2(aq), additional molecules of HCl and ... First, we will write the chemical equation with the formulas of the reactants ... The chloride ions are the only spectator ions I THINKS
Explanation:
15. Calculate the hydrogen ion concentration of a
solution whose pH is 2.4
A 3.6 x 0.01
B 2.5 x 0.0001
C 2.5 x 0.01
D 7.0 x 0.01
Answer:
Explanation:
pH = − log [H+] , we can solve for [H+] as,
− pH = log [H+] ,
[H+] = 10^−pH,
so PH =2.4 in you case is
[H+] = 10^-2.4 =0.00398
The option are not correct it looks
What shape would a molecule with two bound groups and two lone pairs
have?
A. Trigonal pyramidal
B. Tetrahedral
C. Linear
D. Bent
Answer:
It would have to be D, a bent shape
Explanation:
I just took the quiz
A.
B.
C.
D.
what’s the correct answer?
Answer:
C Gamma Rays
Explanation:
Radio waves, on the other hand, have the lowest energies, longest wavelengths, and lowest frequencies of any type of EM radiation. In order from highest to lowest energy, the sections of the EM spectrum are named: *gamma rays* ,X-rays, ultraviolet radiation, visible light, infrared radiation, and radio waves.
What takes place in a cell's mitochondria ?
A.cellular respiration
B.DNA replication
C.protein synthesis
D.photosynthesis
I NEED HELP ASAP!!!!!!!!!!!!!!!!!!!!!!!!
Answer:
c
Explanation:
the mitochodria is the protien power house of the cell
The density was of a solution of sulfuric acid is 1.285g/cm3 and it is 38.08% (by weight) acid. How many millimeters of the acid solution do you need to supply 125 grams of sulfuric acid?
Answer:
255.5cm³
Explanation:
A solution that is 38.08 % by weight has 38.08g of sulfuric acid per 100g of total solution. Thus, mass of solution you need to obtain 125g is:
125g H₂SO₄ × (100g solution / 38.08g H₂SO₄) = 328.3g of solution
As density of the solution is 1.285g / cm³, the volume of 328.3g is:
328.3g × (1cm³ / 1.285g) = 255.5cm³
MY ELEMENT IS SODIUM
1. Summarize the physical and chemical properties of the element you selected.
2. In the lesson, many models were used to depict the atom. How did these models help you understand atomic structure?
3. How do protons, neutrons, and electrons differ in terms of their electrical charges and locations within the atom?
4. Describe the four fundamental forces. Which of these forces are involved in chemical bonding?
Please answer these questions or at least one.
Answer:
Explanation:
1. The element you selected is Sodium. some of the physical properties are
i. Sodium has a strong metallic lustre
ii. Sodium are usually silver white in color
iii. Sodium is soft it can be cut with knife
iv. Sodium are malleable and ductile.
v. Sodium conduct electricity
Sodium belong to group 1 elements which are called Alkali metals. Sodium have one valency electron and it gives this electron easily during bonding . This is one reason sodium and other alkali metals are very reactive. Sodium can instantly be oxidized by water. Sodium has a relative atomic mass of approximately 23 amu.
2. There are various models that describe atoms .This models includes John Dalton models, J.J Thompson model, Ernest Rutherford model, Bohr's models etc. This models made us understand the role and location of each sub atomic particles. The models shed more light on subatomic particles like electron which revolve around the nucleus. It provide more information on what contribute to the weight of an atom.
3. The proton , neutron and electron are subatomic particles of an atom. The proton and the neutron are located at the nucleus of an atom. The proton and neutron contributes majorly to the weight of an atom. The proton is positively charge while neutron has no charge.
Electron is found to move around the nucleus in cloud. The electron is negatively charge. The electron determines bonding of atoms. An atom is electrically neutral if the number of proton is equal to the number of electron.
4. The four fundamental forces includes weak nuclear forces , strong nuclear forces , gravity and electromagnetic forces.
Weak nuclear forces is responsible for particle decay .Nuclear forces don't play a role in chemical reaction . If they are involve in a reaction it becomes nuclear reaction not chemical reaction.
Strong nuclear forces causes a strong nuclear interaction and it is the strongest among the 4 fundamental forces. This strong force only operate when subatomic particles are much closer to each other.
Gravity force is too weak to affect chemical reaction much. The gravity forces involves the interaction between two objects with energy and mass.
The electromagnetic force act between charged particles like negatively charged electron and positively charged proton. Electromagnetic force is the most important force in chemical bonding as it depends on the arrangement of atoms and the state of their electron. Electromagnetic forces exist in various forms like the covalent bond, metallic, ionic , dipole dipole, hydrogen bonds and many more. The major force involve in chemical bonding is the electromagnetic force.