Answer:
climate change
Explanation:
climate change is driving force of evolution because when the climate is changed the animal and human need to adapt to it's natural change.
A TLC plate showed 2 spots with Rf values of 0.25 and 0.26. The plate was removed from the developing chamber, the residual solvent was allowed to evaporate from the plate, and then the plate was returned to the developing chamber. What would you expect to see after the second development was complete
Answer:
See explanation
Explanation:
TLC is a chromatographic method in which the solute is spotted on a plate and the plate is placed in an air tight chamber containing a solvent. The solvent is maintained below the level of the spot. The capillary movement of the solvent through the plate achieves the required separation.
If two spots have Rf values of 0.25 and 0.26 respectively and then the plate was removed from the developing chamber, subsequently, the residual solvent was allowed to evaporate from the plate, and then the plate was returned to the developing chamber.
It will be observed after the second development is complete that the new Rf values will be 0.50 and 0.52 respectively. It will just be as though the second chromatogram picked up from where the first chromatogram stopped.
Molybdenum (Mo) crystallizes with a body-centered cubic lattice and has an atomic radius of 136.1 pm.
a. Calculate the density of molybdenum in g/cm^3. Show all work. Include units with all numbers and show how units cancel.
b. Calculate the density of molybdenum in g/cm^3
Describe what happens between the valence electrons in an Ionic Bond.
How is that different from a covalent bond?
Answer:
In an ionic bond, the elctrons are transferred. For example, NaCl has an ionic bond because Na loses an electron and the Cl atom gains the electron. However in a covalent bond, the electrons are shared equally. Covalent bonds usually occur between two nonmetals.
Explanation:
Hydrogen gas can be prepared in the laboratory by a sin- gle-displacement reaction in which solid zinc reacts with hydrochloric acid. How much zinc in grams is required to make 14.5 g of hydrogen gas through this reaction
Answer:
941 g
Explanation:
Step 1: Write the balanced equation
Zn + 2 HCl ⇒ ZnCl₂ + H₂
Step 2: Calculate the moles corresponding to 14.5 g of H₂
The molar mass of H₂ is 1.01 g/mol.
14.5 g × 1 mol/1.01 g = 14.4 mol
Step 3: Calculate the number of moles of Zn required to form 14.4 moles of H₂
The molar ratio of Zn to H₂ is 1:1. The moles of Zn required are 1/1 × 14.4 mol = 14.4 mol.
Step 4: Calculate the mass corresponding to 14.4 moles of Zn
The molar mass of Zn is 65.38 g/mol.
14.4 mol × 65.38 g/mol = 941 g
A cell is placed into a 1 millimolar solution of substance X. Over time you witness the concentration of X inside the cell increase to 5 millimolar. Describes the movement of substance X?
Answer:
X is moving into the cell by active transport
Explanation:
According to Oxford dictionary;active transport refers to ''the movement of ions or molecules across a cell membrane into a region of higher concentration, assisted by enzymes and requiring energy''.
Since the concentration of X is higher inside the cell than it is outside the cell, energy must be required in order to move substance X across the cell membrane against existing concentration gradient. This process is called active transport.
What is the mass of 2.7 L of water?
how has society influenced our opinions on lithium mining
Answer:
LIBs have had a huge impact on our society. They enabled modern portable electronics such as laptops and mobile phones. And they are now enabling clean and low-carbon transport, be it via electric cars or even flying taxis, and grid-scale storage of renewable energy
Explanation:
Trộn 100ml dung dịch H2SO4 0,03M với 200ml dung dịch HCl 0,03M và 0,001mol Ba(OH)2 0,05M . Hãy tính pH của dung dịch này?
Answer:
pH = 1.92Explanation:
[H+] = 0.1x0.03x2 + 0.2x0.03 = 0.012 mol
[OH-] = 0.001x0.05x2 = 0.0001 mol
=> [H+] dư = 0.012 - 0.0001 =0.0119 mol
pH = -log[H+] = 1.92
Bacteria and archaea carry out the process of nitrogen fixation, which reduces atmospheric nitrogen, N2, to the biologically useful form NH3, also called ammonia. The nitrogenase complex consists of two proteins, reductase and nitrogenase, which catalyze the reactions of nitrogen fixation. Match each structural feature or function with the corresponding component of the nitrogenase complex.
a. also called the molybdenum—iron protein, or the MoFe protein
b. transfers electrons from a donor, such as frrredoxin, to the other component.
c. Homodimer
d. Heterotetramer
1. Reductase
2. Nitrogenase
Answer:
a. Nitrogenase
b. Reductase
c. Reductase
d. Nitrogenase
Explanation:
Reductase is a enzyme which promotes chemical reduction for a substance. It is also known as iron protein as iron is main component in reductase. Nitrogenase are molybdenum because they sulfur as co factor
An aqueous solution was created by placing 0.018 g of NaCl into a 50 mL volumetric flask and diluting to volume with deionized water. (Because the amount of solute is small, you may assume that the volume & density of the solution is equal to the volume & density of the solvent where appropriate.)Find the concentration in terms of the following units. Report your answers without scientific notation.Only input numbers. Your answers must be expressed to the correct number of significant figures. Any values less than one must have a zero in front of the decimal (e.g. 0.01 not .01)Molarity (M): Molality (m):Mole fraction of NaCl (X):Mass % of NaCl:
Answer:
Molarity: 6.2x10⁻³M NaCl
Molality: 6.2x10⁻³m NaCl
Mole Fraction: 1.1x10⁻⁴
Mass% NaCl: 0.036% (m/m NaCl)
Explanation:
Molarity -Moles NaCl / L-
Moles NaCl -Molar mass: 58.44g/mol-
0.018g * (1mol/58.44g) = 0.000308 moles NaCl
Liters water:
50mL * (1L/1000mL) = 0.050L
M = 0.000308 moles NaCl / 0.050L
M = 6.2x10⁻³M NaClMolality -Moles NaCl / kg water-
Moles NaCl = 0.000308 moles NaCl
kg water = 50mL * (1g/mL) * (1kg/1000g) = 0.050kg
m = 0.000308 moles NaCl / 0.050kg
m = 6.2x10⁻³m NaClMole Fraction -Moles NaCl / Moles water+ Moles NaCl-
Moles water = 50g * (1mol/18.01g) = 2.776 moles
Moles fraction = 0.000308 moles NaCl / 0.000308 moles NaCl + 2.776moles water
Mole fraction = 1.1x10⁻⁴Mass Percent -Mass NaCl / Mass NaCl+Mass Water * 100
0.018g / 50g+0.018g * 100
0.036% (m/m NaCl)
Identify each of the following sets of quantum numbers as allowed or not allowed in the hydrogen atom.
a. n=3 , l= 2 , ml =2
b. n=4 , l= 3 , ml =4
c. n=0 , l= 0 , mb =0
d. n=2 , l= 1 , mb =1
Answer:
See explanation.
Explanation:
Hello there!
In this case, according to the given information, it turns out possible for us to firstly recall the electron configuration of hydrogen:
[tex]1s^1[/tex]
To realize that the principal quantum number is 1, the angular is 0 as well as the magnetic one; therefore we infer that all the given n's are not allowed, just l=0 is allowed as well as ml=0 yet the rest, are not allowed.
Best regards!
Spell out the full name of the compound.
Submit
Help plz
Explanation:
A=Butan-2-one
B=Pentan-3-one
explain why seeing a gas doesn not always indicate that there was a chemical change.
Nuclear reactions take place inside the nucleus of the atom. Which of the following does NOT represent an everyday example of a nuclear reaction?
Conversion of carbon dioxide and water in photosynthesis
Hydrogen atoms fused together in the Sun
Loss of protons and electrons in plutonium-240 decay
Energy produced by the Sun that is transferred to Earth
Answer:
Loss of protons and electrons in plutonium 240 decay is not an example of an everyday reaction
How many atoms are in 2.32 mol2.32 mol of copper?
Answer:
since 1 mole = 6.022×10^23
hence in 2.32 moles no. of atoms= 6.022×10^23 × 2.32
=
13.97104 ×10^23
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The following compounds all show a single line in their 1H NMR spectra. List them as they would appear in an NMR spectrum, e.g. by decreasing chemical shift with the lowest shift to the right. These compounds would appear in a spectrum in the order.
a. Benzene
b. CH4
c. Cyclohexane
These compounds would appear in a spectrum in the order: _
Answer:
Benzene < Cyclohexane < CH4
Explanation:
The location of a peak in an NMR spectrum is determined by chemical shift. In 1H NMR, a proton that is strongly shielded, It implies a proton that has a high electron density, is exposed to a low magnetic field, which causes the chemical shift to diminish, resulting in a signal towards the right direction of the spectrum.
However, a de-shielded proton with its electron density reduced is exposed to a high magnetic field, which causes and resulted in a chemical shift and causes it to shift to the left of the spectrum.
Electronegativity is one of the factors that influence the electron density because it decreases the proton's electron density attached to it as well as the ones attached to nearby atoms due to the inductive effect. The impact of an electronegative atom diminishes fast as the distance between them grows.
We can utilize the impact of electronegativity to calculate how much chemical shift will take place in each molecule in this question.
The chemical shift for benzene is = 7.26 ppm
Chemical shift for cyclohexane is = 1.44 ppm
Chemical shift for methane = 0.23 ppm
Thus, in decreasing order, the chemical shift with the lowest shift from left to right is:
Benzene < Cyclohexane < CH4
What are the geometrical shape of BeCl2 and CO2?
Answer:Answer: BeCl2 And CO2 Both Molecules Have The Same - OOOOOOO Molecular Geometry (molecular Shape) Number Of Covalent Bonds To The Central Atom Total Number Of Each Type Of Bond (single, Double, Triple) Number Of Electron Pairs Around The Central Atom Electron Region Geometry (3-D Arrangement Of Electron Pair Regions
Explanation:
9) Give the set of four quantum numbers that could represent the extra electron added (using the Aufbau principle) to the neutral Ne atom.
10) Which 2nd period element has the most negative electron affinity? Why? Bonus questions
11) Which ionization process requires the most energy? Why?
A) Se(g) → Set(g) + e-
B) Set(g) Se2+(g) +
C) Br(g) → Brt(g) + e-
D) Brt(g) Br2+(g) + e-
12) Place the following in order of decreasing metallic character. Explain your reason.
P As K
Answer:
See explanation
Explanation:
9) If an extra electron is added to the neon atom, then the electronic configuration becomes; 1s2 2s2 2p6 3s1
This last electron has quantum numbers;
n=3, l=0, m=0 and s = +1/2
This is so because the 2s level is already filled so the extra electron must go into the 3s level. The orbital quantum number and the magnetic quantum number for the s orbital is zero.
10) Electron affinity is the energy released when one mole of gaseous atoms accept one mole of gaseous electrons to form one mole of gaseous ions having a negative charge.
In the second period, fluorine has the greatest electron affinity since electron affinity increases across the period. The noble gas, neon has an electron affinity of 0KJ/mol.
11) Ionization energy decreases down the group but increases across the period due to increase in the size of the nuclear charge and decrease in the distance between the nucleus and the outermost electron. Hence, the process; Br+(g) ---->Br2+(g) + e- has the greatest ionization energy. Recall that the second ionization is always higher than the first ionization energy.
12)The order of decreasing metallic character here is K> As> P. Even though As and P belong to the same group, we must note that metallic character increases down the group hence the order written above.
If you keep adding sugar to water and there comes a point that you cannot dissolve any more sugar to it then this is called
Answer:
.
Explanation:
Which of these increases the friction of someone walking on the floor?
Answer:
.This is because gravity pulls down harder on the heavier one, which increases its friction with the floor
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which is a characteristic of oxygen
Answer:
Characteristics of oxygen are as follows:
In normal conditions oxygen is a colourless, odourless and insipid gas.It condensates in a light blue liquid.Oxygen is part of a small group of gasses literally paramagnetic and it's the most paramagnetic of all.Liquid oxygen is also slightly paramagnetic.What mass of octane (in g) is required to produce 8210 kJ of heat?
Answer:
184.8 g
Explanation:
Step 1: Write the balanced thermochemical equation
C₈H₁₈(l) + 25/2 O₂(g) ⇒ 8 CO₂(g) + 9 H₂O(g) ΔH°rxn = -5074.1 kJ
Step 2: Calculate the moles of octane required to produce 8210 kJ of heat
According to the thermochemical equation, 5074.1 kJ of heat are released per mole of octane consumed.
-8210 kJ × 1 mol C₈H₁₈/(-5074.1 kJ) = 1.618 mol
Step 3: Calculate the mass corresponding to 1.618 moles of octane
The molar mass of C₈H₁₈ is 114.23 g/mol.
1.618 mol × 114.23 g/mol = 184.8 g
1mol produces=5074.1KJ heat .
Moles produce 8210 KJ heat :-
8210/5074.1=1.62molMolar mass of Octane :-
8(12)+18=96+18=114g/molMass of Octane=
1.62(114)=184.7gHow would you prepare stable polymers from formaldehyde?
Answer:
The mechanical properties of urea formaldehyde resins may be improved by incorporating therein polyvinyl alcohol. The polyvinyl alcohol may be incorporated during pre-mixing, mid mixing, and/or post mixing of the resin components. Resins prepared using polyvinyl alcohol are particularly desirable in articles requiring improved mechanical strength and water resistance, as compared to similar resins prepared without the polyvinyl alcohol such as shingles.
You have a sample of gold that contains 0.2 moles of gold (Au). How many gold atoms are present in the sample. HINT: Gold atoms represents the number of particles."
1.20 x 10^23 atoms
3.3 x 10^-25 atoms
1.01 x 10^-3 moles
BEST ANSWER IS
have a great summer
1.01 x 10^-3 moles
n = 0.20 mol
Required:N
Solution:N = n × 6.02 × 10²³ atoms/mol
N = 0.2 mol × 6.02 × 10²³ atoms/mol
N = 1.20 × 10²³ atoms
Therefore, there are 1.20 × 10²³ gold atoms in 0.2 mol of a gold sample.
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Complete the sentence.
Hexene would have _ carbon atoms and one _ bond
First blank options:
7, 8, 1, 2, 4, 3, 5, 6
Second blank options:
single, double, triple
Answer:
6, double
Explanation:
Hex- is a prefix for number 6.
Ene- is a suffix for a double bond.
Which is a property of barium (Ba)?
O A. It rarely reacts with other elements.
O B. It is brittle as a solid.
O c. It is very reactive.
O D. It does not conduct electricity.
Plzzzzz helppppp!!!
Answer:
a it rarely reach with other elements
Question 11
1 pts
A solution is formed by dissolving 45 grams of NH4Cl in
100 grams of H20 at 70°C. Which statement correctly
describes this solution?
O NH4Cl is the solute, and the solution is saturated.
O NH4Cl is the solute, and the solution is unsaturated.
o NH4Cl is the solvent, and the solution is unsaturated.
O NH4Cl is the solvent, and the solution is saturated.
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Answer:
NH4Cl is the solute, and the solution is unsaturated.
Explanation:
To create a saturated solution of ammonium chloride at 70°C, we need to dissolve 62 g of ammonium chloride in 100 g of water.
The question tells us that 45 grams of NH4Cl was dissolved in 100 grams of H20 at 70°C. This creates an unsaturated solution since the amount of solute present is less than the amount of solute that the NH4Cl solution can normally hold at 70°C.
Hence, NH4Cl is the solute, and the solution is unsaturated.
Fabric A is used to rub a wooden rod. A second piece of Fabric A is used to rub an ebonite rod. It is observed that the wooden rod and the ebonite rod attract one another. What can you say about the position of Fabric A in the electrostatic series in relation to wood and ebonite?
Fabric A is likely to be a material that has a moderate tendency to gain electrons when in contact with other materials and is lower in the electrostatic series than ebonite but higher than wood.
What is electrostatic series?The electrostatic series is a list of materials ranked in order of their tendency to gain or lose electrons when in contact with another material.
Materials higher in the series tend to lose electrons more readily and become positively charged, while materials lower in the series tend to gain electrons more readily and become negatively charged.
Ebonite is a synthetic polymer that is known to become negatively charged when rubbed, and it is typically placed near the top of the electrostatic series.
Wood, on the other hand, is a poor conductor of electricity and does not readily become charged when rubbed. Based on these facts, we can infer that Fabric A is lower in the electrostatic series than ebonite, but higher than wood.
To learn more about an electrostatic series, follow the link:
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The literature values listed for the unknowns in this assignment are from either the Merck Index or the CRC Handbook, the two most used reference handbooks. However, the values tend to vary slightly across literature sources and sometimes the temperatures are given as ranges. Give at least one reason for the variations in these reported temperatures.
In general, the boiling points of compounds increase down a group in the periodic table. The melting points and boiling points for the hydrogen compounds of group 6A elements are in the table below.
Melting point (0C) Boiling point (oC)
H2O 0.0 100.0
H2S -82.0 -60.0
H2Se -65.7 -41.2
H2Te -49.0 -2.2
Answer:
See explanation
Explanation:
One of the important trends in the periodic table is electronegativity. Electro negativity decreases down the group and increases across the period. This trend has important consequences on the observed properties of the compounds of elements in a particular group in the periodic table.
As we move down in group 6A, the electro negativity of the elements elements the group decrease and as such, the magnitude of intermolecular hydrogen bonding between the molecules also decrease accordingly. Hydrogen bonds occur between
molecules of a substance when hydrogen is covalently bonded to an electronegative element. Hydrogen bonding is responsible for the high melting and boiling points of small molecules such as water which contain the highly electronegative oxygen atom.
So, as we move down the group there is lesser intermolecular hydrogen bonding between the hydride molecules of group 6A elements resulting in the observed trend in melting and boiling points of the hydrides.
The weaker hydrogen bonds that occurbetween molecules of group 6A hydrides lead to a steady decrease in melting and boiling points of the hydrides of group 6A elements as we move down the group.
3. Calculate the answers to the appropriate number of significant figures. e) 43.678 x 64.1 = f) 1.678/0.42 =