Chemical middle School
Peptides consist of 10 or more amino acids linked by covalent bonds called peptide bonds.
A peptide bond is formed when the alpha-carboxyl group of one amino acid reacts with the alpha-amino group of another amino group to form a CO-NH bridge.
Covalent linkage of two amino acid residues of a dipeptide to three amino acid residues of a tripeptide. A continuous polymerization of 10 or more amino acids is called a polypeptide. When there are 50 or more amino acids linked by peptide bonds, it is called a protein.
Chlorine has two isotopes, 35Cl and 37Cl, with percentage abundances of 75.77% and 24.23%, respectively, and masses of 34.9688 amu and 36.9659 amu. Calculate the atomic mass of chlorine.
The answer to your question is 35.4527 g
Cl-35 abundance = 75.77% mass Cl-35 = 34.9688
Cl-37 abundance = 24.23% mass Cl-37 = 36.9659
1.- Convert percentages to decimals
75,77% = 75,77/100 = 0,7577
24,23 % = 24,23/100 = 0,2423
2.- Find the atomic masses
Average Atomic Weight = Abundance 1 x Cl-35 Mass Number +
Abundance 2 x mass of Cl-37
Average atomic weight = (0.7577)(34.9688) + (0.2423 x 36.9659)
Average atomic weight = 26.4959 + 8.9568
Average atomic weight = 35.4527 grams
In the vinegar analysis laboratory, at the end of the titration, a drop of NaOH solution still hangs from the tip of the burette. How does this affect the experimental results in this laboratory?
At the equivalence point of the titration, only one drop of NaOH is needed to change the entire solution in the Erlenmeyer flask from colorless to very pink.
At the equivalence point, all the acetic acid in the vinegar is completely consumed by the NaOH. So we use the indicator phenolphthalein to illustrate this.
Neutralization occurs when sodium hydroxide and sulfuric acid are mixed. If 2.26 grams of sodium hydroxide are mixed with 4.19 grams of sulfuric acid, what is the amount of water and sodium sulfate when the reaction is complete? How do you go about solving the problem?
The dose of sodium sulfate is 5.64 g.
The amount of water is 1.017g
First give the equilibrium equation for the reaction.
2NaOH + H2SO4 > Na2SO4 + 2H2O
Find the number of moles of each reactant species by dividing the mass by its molar mass.
Using moles to find the amount in a product
0.02825 x molar mass of 2H2O = 1.017g
0.0428 x 132 = 5.64 grams
A chemist needs 2.00 liters of 0.200 M K2Cr2O7 (potassium dichromate) in water. How many grams of solid K2Cr2O7 must be weighed to make this solution?
The correct answer is 117.68 grams.
To calculate the mass that a chemist needs to weigh, we must multiply the concentration of the solution (0.200 M) by the volume (2.00 L). Since the concentration is in M (mol/L), we must first convert the concentration from molarity to g/L using the molecular weight of K2Cr2O7.
From the periodic table we know the molar masses (MM) of the elements K, Cr and O:
Molekylvægt K2Cr2O7= (2 x MM K) + (2 x MM Cr) + (7 x MM O)
Molekylvægt K2Cr2O7= (2 x 39,1 g/mol) + (2 x 52 g/mol) + (7+ 16 g/mol)
Peso molecular K2Cr2O7= 294,2 g/mol
Finally, we can calculate the mass as follows:
Mass = 0.200 mol/L x 294.2 g/mol x 2.00 L= 117.68 g
Classify the acids according to their expected pKa values. Order of ClCH2COOHClCH2CH2COOHCH3CH2COOHCl2CHCOOH from highest pka to lowest pka
CH3CH2COOH < CLCH3CH2COOH
An aqueous glucose solution with a density of 1.04 g/cm3 freezes at –1.15°C. Find the osmotic pressure of this solution at 25°C. Kf for water is 1.86°C/m; the molecular weight of glucose = 180.16 g/mol.
1,15 = metro x 1,86
m = 0,618 => 0,618 mol i 1 kg vand
Glucose by mass = 0.618 mol x 180.16 g/mol = 111.3 g
Mass solution = 1000 g + 111.3 = 1111 g
Solution volume = 1111 / 1.04 g/cm^3 = 1069 cm^3 = 1.069 dm^3
Molarity = 0.618/1.069=0.578
Osmolalitet = M x R x T = 0,578 x 0,08206 x 298
The depolarization phase of the action potential requires _____. The depolarization phase of the action potential requires _____. Opening of the K channel in the membrane Ca2 concentration gradient across the membrane K concentration gradient across the membrane Opening of the Ca2 channel in the membrane Opening of the Na channel in the membrane
Opens Na channels in the membrane.
Depolarization is the mechanism by which channels in membranes open or close. Depolarization of the action potential requires the opening of Na channels in the membrane, which increases the membrane potential by increasing the influx of Na ions
Thomas poured 25 mL of 0.60 M HCl into a large bottle. He then added enough water to make the new (diluted) concentration of 0.10 M HCl. How much water did Thomas add?
The answer to your question is 150ml
Volume 1 = 25mL
Concentration 1 = 0.6M
Link 2 = ?
Concentration 2 = 0.1M
Volume 1 x Concentration 1 = Volume 2 x Concentration 2
Solution volume 2
Volume 2 = (volume 1 x concentration 1) / concentration 2
Volumen 2 = (25 x 0,6) / 0,1
Link 2 = 15 / 0.1
Volume 2 = 150mL
Two ways that chemistry affects you in your daily life?
When you do the dishes when you take a shower, I appreciate you putting them in a complete sentence that would be good answers.
A bar of iron has a mass of 537 g. After a bar of gold has been in the air for one month, exactly one eighth of the iron has oxidized (Fe2O3). Calculate the final mass of the iron bar and the rust.
The answer to your question is the mass of the iron bar = 469.87 g
Oxide mass = 67.13 g
Iron bar mass = 537 g
1/8 turn rusty
Final mass of the iron bar = x
Final quality of the oxide = ?
1.- Divide the total dough by eight (number of parts)
537 grams /8 = 67.13 grams
2.- The final mass of the oxide is 1/8 = 67.13 g
3.- Calculate the final mass of the iron bar
67.13 x 7 = 469.87 grams
Hydrogen bonds form between adjacent water molecules due to ________. A. Transfer of electrons B. Sharing of electrons C. Viscosity of water D. Polarity of water molecules E. Surface tension
The answer is b.
Hydrogen bonds are formed when hydrogen atoms are attracted to oxygen atoms in other waters. Protons are shared by two pairs of ions and electrons, where the oxygen atom has a partially negative charge and the hydrogen atom has a partially positive charge.
Dissolve 0.285 mol of CaCl2(s) in enough water to make a 1.2 liter solution. What is the molarity (molarity) of the solution?
The answer to your question is molarity = 0.238
molar concentration = ?
Mol = 0,285
volume = 1.2 liters
Molarity is a unit of concentration that relates the number of moles of a substance to a volume in liters.
Molarity = mole/volume
Molarity = 0.285 / 1.2
simplification and result
Molarity = 0.238
When you walk on a carpeted floor, more electrons enter your body than when you walk on a smooth floor. What is the most likely explanation for this?
The answer is explained as follows:
Your feet rub against the electrons on the carpet, so when we walk on a carpeted floor, more electrons enter our body due to static electricity. Static electricity is a fixed electrical charge, usually created by friction.
How many moles of SnCl2 will be produced if 85.3 g of FeCl3 react with an excess of Sn as follows: 2 FeCl3(s) + 3 Sn(s) → 3 SnCl2(s) + 2 Fe(s)
The answer to your question is 0.79 mol of SnCl2
The number of moles of SnCl2 = ?
Mass of FeCl3 = 85.3 g
balanced chemical reaction
2 FeCl3 + 3 Sn ⇒ 3 SnCl2 + 2 Fe
1.- Convert the mass of FeCl3 to moles
Molar mass of FeCl3 = 56 + (35.5 x 3)
= 56 + 106,5
= 162,5 grams
Use the scale to find moles of FeCl₃
162,5 g ------------------ 1 mol
85.3 gram ------------------ x
x = (85,3 x 1) / 162,5
x = 0,525 moles
2.- Find the number of moles of SnCl2
2 mol FeCl3 ------------------ 3 mol SnCl2
0,525 moles ------------------ x
x = (0,525 x 3) / 2
x = 0.79 mol SnCl2
Hydrogen and iodine react to form hydrogen iodide gas. What is the value of Keq for this reaction if the equilibrium concentrations of H2, I2, and HI are 0.25 M, 0.035 M, and 0.55 M, respectively?
The answer to your question is Keq = 34.57
[H2] = 0,25M
[I2] = 0.035M
[height] = 0.55m
balanced chemical reaction
H2 + I2 ⇒ 2 alto
The coefficient of HI will be the exponent.
差 = [HI]² / [H₂][I₂]
Difference = [0.55]² / [0.25][0.035]
Difference = 0.3025 / 0.00875
Difference = 34.57
The Keq value of the equilibrium constant for the reaction with 0.25 M H2, 0.035 M I2, and 0.55 M HI at equilibrium is 34.57
Data taken from the question.
- Brintconcentración [H2] = 0,25 M
- Jodconcentration [I2] = 0.035 M
- Hydrogen iodine concentration [HI] = 0.55 M
- Constante de equilibrio (Bad) = ?
H2 + I2 2HI
How to Determine the Equilibrium Constant
The equilibrium constant of the reaction can be obtained from the following formula:
差 = [HI]² / [H₂][I₂]
Difference = [0.55]² / [0.25][0.035]
Difference = 0.3025 / 0.00875
Difference = 34.57
Therefore, the equilibrium constant of the reaction is 34.57
Learn more about equilibrium constants:
You measured the volume of gas as 2.5 liters, but you are wrong with the unit, it actually represents 2.5 ml (theoretically). What is your error rate?
Answer: The error rate is 99900%.
To calculate the percent error, we use the following equation:
Volume experimental value = 2.5 L
Acceptable volume value (theoretical) = 2.5 mL = 0.0025 L (1 L = 1000 mL)
If we put the values in the above equation, we get:
Therefore, the percent error is 99900%.
What causes water to become denser as surface currents carry it to the poles? Temperature increase and salinity increase Temperature decrease and salinity decrease Temperature increase and salinity decrease Temperature decrease and salinity increase
The answer is lower temperature and higher salinity.
This is called thermohaline circulation.
The heat-salt cycle moves water slowly. This movement of water is mainly due to the difference in their relative density. Much denser water sinks into less dense water. Two factors affect the density of seawater: temperature and salinity.
Cold water is more dense than hot water:
- Water cools when it loses heat, which happens at high latitudes.
- In low latitudes, the water is heated by receiving energy from the sun.
Water with a high salinity content is much denser than water with a low salinity content:
- If the evaporation rate increases, seawater becomes saltier.
- If there is a water intake in the sea, the sea water will be less salty.
D. Lower the temperature and increase the salinity
The rate limiting step in a reaction is the slowest step in the reaction sequence. The rate limiting step in a reaction is the slowest step in the reaction sequence. true and false]
The statement is correct.
- The rate limiting step in a reaction is also known as the rate limiting step.
- This is the slowest step in the entire reaction sequence.
- Since the rate-limiting or rate-determining step is the slowest step that occurs in the entire reaction sequence, it determines the rate or rate of the reaction as a whole.
- Therefore, the statement given that the rate-limiting step in a reaction is the slowest step is true.
In a medical test designed to measure carbohydrate tolerance, an adult drinks 5 ounces of a 20 percent glucose solution. When testing children, the glucose concentration should be reduced to 10%. How much 20% dextrose solution and how much water must be used to make 5 ounces of 10% dextrose solution?
10% dextrose should be made with 2.5 ounces of 20% dextrose and 2.5 ounces of water.
given = required
C1xV1 = C2xV2
20xV1 = 10x5
V1 = (10x5) / 20
= 2.5 ounces of 20% glucose
Dilution factor = total amount - V1 (amount given)
= 5 - 2,5
= 2.5 ounces
Take 2.5 ounces of 20% dextrose and add 2.5 ounces of water to make a total of 5 ounces.
Also simple, since the percentage concentration is halved, a 1:2 dilution is used, which means that 2.5 ounces of 20% dextrose and 2.5 ounces of water will total 5 ounces of solution.
A gas sample sealed in a rigid metal container at room temperature (20.0∘C∘C) has an absolute pressure p1p1p_1. Immerse the container in hot water until it warms to 40.0∘C∘C. What is the new absolute pressure p2p2p_2? Express your answer as p1p1p_1.
Answer: p2 = 1.06p1
Explanation: Pressure increases with temperature.
According to Gay's law
P1/T1 = P2/T2
T1 = 20°c = 20 +273 = 293k
T2 = 40°c = 40 +373 = 313k
P2 = P1T2/T1 = 313P2/293
P2 = 1,06P1
When two amino acids are linked, the amino group of one amino acid is linked to the acid group of the other amino acid as follows? ›
2: Peptide Bonds. A peptide bond forms when the amino group of one amino acid bonds to the carboxyl group of another amino acid. A peptide is two or more amino acids joined together by peptide bonds, and a polypeptide is a chain of many amino acids.What happens when two amino acids are linked together? ›
A dipeptide is formed when two Amino acids join together by one Peptide bond. This happens via a Condensation Reaction. The bond between the two amino acids forms between the carboxyl group on one and the amino group on another, therefore producing a water molecule as a product.What is the link between two amino acids called? ›
In a similar reaction, the amino group on one amino acid molecule reacts with the carboxyl group on another, releasing a molecule of water and forming an amide linkage: An amide bond joining two amino acid units is called a peptide bond.When two amino acids are linked together a peptide bond is formed between the group of one and the group? ›
Answer and Explanation: The amino acid acids are joined together by peptide bond to form short polymer chain called Peptide or long polymer chain called Protein. The peptide bond is formed between the amino group of one amino acid with carboxylic acid group of another amino group by eliminating water molecules.What happens after amino acids have been linked together in the ribosome? ›
Ribosomes provide a structure in which translation can take place. They also catalyze the reaction that links amino acids to make a new protein. tRNAs (transfer RNAs) carry amino acids to the ribosome. They act as "bridges," matching a codon in an mRNA with the amino acid it codes for.Which bond links multiple amino acids together what is it called quizlet? ›
This bond links multiple amino acids together, what is it called? Peptide bonds. This polypeptide chain represents the primary structure of a protein.What type of bond is formed as two amino acid are combined together? ›
Peptide bonds are amide bonds between the α-carboxyl group of one amino acid and the α-amino group of another (Fig. 3-1).What is the end result of amino acids joining together in translation? ›
As tRNAs enter slots in the ribosome and bind to codons, their amino acids are linked to the growing polypeptide chain in a chemical reaction. The end result is a polypeptide whose amino acid sequence mirrors the sequence of codons in the mRNA.What are the bonds that link amino acids together at the ribosome? ›
Peptide Bond Formation
The links between the amino acids are the peptide bonds. Peptide bonds occur by a process called dehydration synthesis.
Stop Codons Mark the End of Translation
This reaction frees the carboxyl end of the growing polypeptide chain from its attachment to a tRNA molecule, and since only this attachment normally holds the growing polypeptide to the ribosome, the completed protein chain is immediately released into the cytoplasm.
What two groups react to form a peptide bond between two amino acids? ›
Explanation: A peptide bond is formed via the condensation of one amino acid's alpha-carboxy group with the alpha-amino group of another amino acid.What is the bond between two amino acids peptide? ›
A peptide bond is a covalent chemical bond linking two consecutive amino acid monomers along a peptide or protein chain.How a peptide bond is formed between two amino acids? ›
A peptide bond forms between two amino acids in a condensation reaction. The bond forms between the carboxyl group of one amino acid and the amine group of the other. This is a condensation reaction, where two molecules react to form one, joined by a bond and includes the removal of water.What does a peptide bond join two amino acids between? ›
A peptide bond, also referred to as an amide bond, is formed between the α-nitrogen atom of one amino acid and the carbonyl carbon of a second. Each amino acid is attached to another amino acid by a covalent bond, known as a peptide bond.What are the bonds that connect amino acids in a protein called? ›
A series of amino acids joined by peptide bonds form a polypeptide chain, and each amino acid unit in a polypeptide is called a residue. So, the correct option is 'Peptide bond'.How is a peptide bond formed between two amino acids quizlet? ›
A peptide bond is formed between two amino acids when the carboxyl group of one amino acids reacts with the amino group of the other amino acid, releasing a molecule of water. This is the dehydration reaction and usually occurs between amino acids.What is the bonding of two amino acids requires? ›
Answer: Each amino acid is attached to another amino acid by a covalent bond, known as a peptide bond. When two amino acids are covalently attached by a peptide bond, the carboxyl group of one amino acid and the amino group of the incoming amino acid combine and release a molecule of water.