Answer:
8 oxygen. 9 flourine. 10. Neon. 5 Boron
Which one of the following compounds shows red precipitate of Cu2O with the reaction of Fehling solution?
a. Vinegar c. Glycerine
b. Formalin d. Propanon
Answer:
acetaldehyde
When acetaldehyde is heated with Fehling's solution, a red precipitate is formed.
Explanation:
Use the heating curve of 60.0 grams of ice and the list of values to answer the question.
A heating curve with the y -axis showing temperatures between -20 degrees Celsius and 15 degrees Celsius and the x-axis showing time. The plot starts at Point A at -20 degrees Celsius and moves diagonally upward and to the right until it reaches Point B, which measures 0 degrees Celsius. Next, the line runs horizontally to the right until it reaches Point C. From Point C the line moves up and to the right to Point D, which measures at 15 degrees Celsius.
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specific heat of ice = 2.10 J/(g·°C)
specific heat of water = 4.18 J/(g·°C)
specific heat of water vapor = 2.07 J/(g·°C)
latent heat of fusion of ice = 333.4 J/g
latent heat of vaporization of water = 2256 J/g
How much energy was added to the ice between Point A and Point D?
25 kJ
150 J
154 J
26 kJ
Answer:
Changes of state occur at segment
✔ B–C
and segment
✔ D–E
Explanation:
got it right on edge :)
The amount of energy added to the ice between Point A and Point D is approximately 25 kJ.
To calculate the amount of energy added to the ice between Point A and Point D, we need to consider the different stages of the heating curve.
Heating the ice from -20°C to 0°C:
The energy required to raise the temperature of the ice can be calculated using the specific heat of ice (2.10 J/(g·°C)) and the mass of the ice (60.0 g). The temperature change is from -20°C to 0°C, which is a total of 20 degrees.
Energy = mass × specific heat × temperature change
Energy = 60.0 g × 2.10 J/(g·°C) × 20°C
Energy = 2520 J
Melting the ice at 0°C:
The energy required to melt the ice can be calculated using the latent heat of fusion of ice (333.4 J/g) and the mass of the ice (60.0 g).
Energy = mass × latent heat of fusion
Energy = 60.0 g × 333.4 J/g
Energy = 20,004 J
Heating the water from 0°C to 15°C:
The energy required to raise the temperature of the water can be calculated using the specific heat of water (4.18 J/(g·°C)) and the mass of the water (60.0 g). The temperature change is from 0°C to 15°C, which is a total of 15 degrees.
Energy = mass × specific heat × temperature change
Energy = 60.0 g × 4.18 J/(g·°C) × 15°C
Energy = 3753 J
The total energy added to the ice between Point A and Point D is the sum of the energy calculated in each step:
Total Energy = Energy (Heating ice) + Energy (Melting ice) + Energy (Heating water)
Total Energy = 2520 J + 20,004 J + 3753 J
Total Energy = 25,277 J
Converting this energy to kilojoules (kJ):
Total Energy = 25,277 J ÷ 1000
Total Energy = 25.277 kJ
Therefore, the amount of energy added to the ice between Point A and Point D is approximately 25 kJ.
To know more about energy
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Determine the percentage of carbon and hydrogen in ethane C2H6 if the molecular weight is 30.
Answer:
Percentage of carbon:
[tex] { \tt{ = \frac{24}{30} \times 100\%}} \\ = 80\%[/tex]
Percentage of hydrogen:
[tex]{ \tt{ = \frac{6}{30} \times 100\%} } \\ = 20\%[/tex]
Whate the mass percentage of Sulphure in Na2so4 ?
Answer:
Water H2O + SULPHATE OXIDE
Classify each cation as a weak acid or pH neutral (neither acidic nor basic).
a. Na+
b. Ni2+
c. NH4+
Answer:
a. Na+ is pH neutral
b. Ni2+ = weak acid
c. NH4+ = Weak acid
Explanation:
To know the nature of the cation we need to find the nature of its conjugate base.
If the conjugate base of the ion is a strong base, the ion is neutral.
If the conjugate base is a weak base, the ion is a weak acid:
a. Conjugate base Na+ = NaOH
Sodium hydroxide is a strong base:
Na+ is pH neutral
b. Conjugate base Ni²⁺: Ni(OH)2 is a weak base because is not completely soluble in water. That means:
Ni2+ = weak acid
c. Conjugate base NH4+: NH4OH. Weak base:
NH4+ = Weak acid
bio-chemisty of protain
Answer:
Protein biochemistry is the study of proteins. Protein biochemistry is a scientific field dedicated to the study of proteins, complex chains of amino acids which make up the building blocks of all living organisms.
Explanation:
I hope that helped
Copy and Pasted!
Answer:
Listen to what guy said on top.
Explanation:
polypeptide structures consisting of one or more long chains of amino acids residue.....
or my answer
Which Group is in the second column of the periodic table?
O A. Noble gases
O B. Alkaline earth metals
O C. Alkali metals
O D. Halogens
Answer:
O B. Alkaline earth metals
Explanation:
Noble gases → 8th column.
Alkali metal → first column.
Halogen → 7th
Answer:
B. Alkaline earth metals
Explanation:
Alkaline-earth metals: The alkaline-earth metals make up Group 2 of the periodic table, from beryllium (Be) through radium (Ra). Each of these elements has two electrons in its outermost energy level, which makes the alkaline earths reactive enough that they're rarely found alone in nature. But they're not as reactive as the alkali metals. Their chemical reactions typically occur more slowly and produce less heat compared to the alkali metals.
A 1.19 g sample of an unknown halogen occupies 109 mL at 398 K and 1.41 atm. What is the identity of the halogen
Answer:
The halogen is Iodine.
Explanation:
Using the ideal gas equation, we find the number of moles of gas present, n.
PV = nRT where P = pressure of gas = 1.41 atm, V = volume of gas = 109 mL = 0.109 L, n = number of moles of gas, R = molar gas constant = 0.082 L-atm/mol-K and T = temperature of gas = 398 K
Since PV = nRT, making n subject of the formula, we have
n = PV/RT
substituting the values of the variables into the equation, we have
n = 1.41 atm × 0.109 L/(0.082 L-atm/mol-K × 398 K)
n = 0.15369 atm-L/32.636 L-atm/mol
n = 0.0047 mol
Since n = m/M where m = mass of gas = 1.19 g and M = relative molecular mass of gas
So, M = m/n
M = 1.19 g/0.0047 mol
M = 252.7 g
Since halogens are diatomic the relative atomic mass is M/2 = 252.7g/2 = 126.34 g
From tables, the only halogen with this atomic mass is Iodine.
So, the halogen is Iodine.
Name the compound CuI2
Answer:
Copper iodide. I think
Answer:
copper iodide(Cul2)hope it helps
stay safe healthy and happy..Cal is titrating 57.7 mL of 0.311 M HBr with 0.304 M Ba(OH)2. How many mL of Ba(OH)2 does Cal need to add to reach the equivalence point?
Answer:
118.06 mL
Explanation:
The neutralization reaction between HBr (acid) and Ba(OH)₂ (base) is the following:
2HBr + Ba(OH)₂ → BaBr₂ + 2H₂O
According to the equation, 2 moles of HBr react with 1 mol Ba(OH)₂. Thus, at the equivalence point the moles of acid and base react completely:
2 moles HBr = 1 mol Ba(OH)₂
We can replace the moles by the product of the molar concentration (M) and volume (V):
2 x (M HBr) x (V HBr) = M Ba(OH)₂ x V Ba(OH)₂
Now, we introduce the data in the equation to calculate the volume in mL of Ba(OH)₂:
V Ba(OH)₂ = (2 x (M HBr) x (V HBr))/M Ba(OH)₂
= (2 x 0.311 M x 57.7 mL)/(0.304 M)
= 118.06 mL
Therefore, 118 mL of Ba(OH)₂ are needed.
22. Glycerol, C3H8O3, is a substance used extensively in the manufacture of cosmetics, foodstuffs, antifreeze, and plastics. Glycerol is a water-soluble liquid with a density of 1.2656 g/mL at 15 0C. Calculate the molarity of a solution of glycerol made by dissolving 50.000 mL glycerol at 15 0C in enough water to make 250.00 mL of solution. Show work.
Answer:
2.75M
Explanation:
Density = mass/volume
Density of glycerol (C3H8O3) at 15°C is given as 1.2656 g/mL.
Volume of glycerol at this same temperature before dissolving in water = 50mL
Hence, using Density = mass/volume
1.2656 = mass/50
mass = 1.2656g/mL × 50mL
mass = 63.28g
Molarity of solution = number of moles (n) ÷ volume (V)
Volume of glycerol dissolved in water = 250mL = 0.250L
number of moles = mass/molar mass
Molar mass of C3H8O3 = 12(3) + 1(8) + 16(3)
= 36 + 8 + 48
= 44 + 48
= 92g/mol
n = 63.28g ÷ 92g/mol
n = 0.688mol
* Molarity = n/V
Molarity = 0.688/0.250
Molarity = 2.75M
Help pls!!!
For groups 13 through 18, the number of valence electrons is equal to the group number
a. minus 10
b. minus the period number
c. plus 1
d. plus the period number
Answer:
a. minus 10
Explanation:
An element in group 13 = Boron ,valence electrons = 3 , therefore, valence electrons in group 13 = group no. -10
An element in group 18 = Neon, valence electrons = 8 , therefore, valence electrons in group 18 = group no. - 10
For groups 13 through 18, the number of valence electrons in an atom is equal to the group number minus 10. Therefore, option (A) is correct.
What is a valence electron?Valence electrons in an atom can be described as the electrons occupying the outer most electron shell of an atom while the electrons in the inner shell are core electrons. Lewis structures can be helpful to calculate the number of valence electrons.
Valence electrons can be filled in several electron shells as they are caused interaction between atoms and responsible for the formation of chemical bonds. Only valence electrons can contribute to the formation of a chemical bond and decide the reactivity of the element.
The general electronic configuration of group 13 is ns²np¹ has three valence electrons. It can be determined as group number - 10 = 13 - 10 = 3.
The general electronic configuration of group 18 is ns²np⁶ has eight valence electrons. It can be determined as group number - 10 = 18 - 10 = 8.
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The metal thallium becomes superconducting at temperatures below 2.39K. Calculate the temperature at which thallium becomes superconducting in degrees Celsius. Round your answer to decimal places.
Answer:
-270.76°C
Explanation:
Given that metal Thallium becomes superconducting below the temperature of 2.39 kelvin i.e. this temperature is critical temperature for Thallium and below critical temperature a metal offers no resistance to the flow of electric current. Also the metal below its critical temperature expels the magnetic field in such a way that they do not penetrate the metal and pass through its surface only.
We have the relation between kelvin scale and degree Celsius scale of temperature measurement as:
[tex]C = K - 273.15[/tex]
[tex]C=2.39-273.15\\ C=-270.76^{o}C[/tex]
According to Newton's law of universal gravitation, how do the masses of two
objects relate to the gravitational force between them?
A. As either mass increases, the gravitational force between them
increases.
B. As either mass increases, the gravitational force between them
decreases.
C. Gravitational force increases only when both masses increase.
D. Gravitational force increases only when both masses decrease.
Answer:
As either mass increases, the gravitational force between them
increases.
Explanation:
According to Newton's law of universal gravitation;
F α m1m2/r^2
That is, the force between two masses in a gravitational field is directly proportional to the product of the two masses and inversely proportional to their distance apart.
Hence, as either of the masses increase, the force of gravitation between the two masses increases. Hence the answer.
A student measured the gram weight of a metal object to be 5.88g. According to the supplier the object weighs 5.97g. What is the error in the student's measurement?
A. -0.09
B. +0.09
Answer:
–0.09
Explanation:
From the question given above, the following data were obtained:
Measured value = 5.88 g
Actual value = 5.97 g
Error =?
The error in the student's measurement can be obtained as follow:
Error = Measured value – Actual value
Error = 5.88 – 5.97
Error = –0.09
Therefore, the error in the student's measurement is –0.09
The action of some commercial drain cleaners is based on the following reaction:
2 NaOH(s) + 2 Al(s) + 6 H2O(l) â 2 NaAl(OH)4(s) + 3 H2(g)
What is the volume of H2 gas formed at STP when 4.32 g of Al reacts with excess NaOH?
A. 3.59 L
B. 2.39 L
C. 5.87 L
D. 5.38 L
Answer:
5.38 L
Option D.
Explanation:
2 NaOH(s) + 2 Al(s) + 6 H₂O(l) → 2 NaAl(OH)₄(s) + 3 H₂(g)
We convert mass of Al to moles:
4.32 g . 1 mol /26.98g = 0.160 moles
As NaOH is in excess, aluminum is the limiting reactant.
We see stoichiometry, were ratio is 2:3.
2 moles of Al can produce 3 moles of hydrogen
Our 0.160 moles may produce (0.160 . 3)/2 = 0.240 moles of H₂.
We know that 1 mol of any gas at STP conditions is contained in 22.4L
So let's make the conversion factor:
0.240 mol . 22.4L / 1mol = 5.38 L
discuss the benefits of observing good safety measures in relation to increase in productivity within a pharmaceutical laboratory?
Answer:
Pharmaceutical laboratory helps in devloping and conducting research, vaccines. Various kinds of drugs and chemical substances used and are produced at a Pharmaceutical laboratory.
The pharmaceutical laboratories performs with various hazardous substances that results in exposure to various chemicals, biological substances and radiation. To avoid any injury or infection labs need to maintain all safety measures.
Spillage and relaseing chemical substances can be lethal during transportaions by safety measures for heling in for manufacturing of such therapeutic agents spillage and avoid wastage.
Maintaining good safety standards in the pharmaceuticals laboratory will help promote the health of technicians and workers which in turn will increase productivity and attain positive outcomes.
What is the theoretical yield of cyclohexene (in grams) that could be formed from 0.105 moles of cyclohexanol and 0.0444 moles of 85% phosphoric acid
Answer:
3.65 g of cyclohexene
Explanation:
Cyclohexanol + phosphoric acid ----> cyclohexene
The reaction is 1:1 hence the limiting reactant is phosphoric acid.
Hence,
1 mole of phosphoric acid yields 1 mole of cyclohexene
0.0444 moles of phosphoric acid yields 0.0444 moles of cyclohexene
Theoretical yield = number of moles of cyclohexene × molar mass of cyclohexene
Theoretical yield = 0.0444 moles of cyclohexene × 82.143 g/mol
Theoretical yield = 3.65 g of cyclohexene
Identify the substance that conducts electricity.
a. Rubbing alcohol.
b. KBr dissolved in water.
c. Solid KBr.
d. Solid baking soda
e. Sugar dissolved in water.
Answer:
KBr dissolved in water.
Explanation:
A substance conducts electricity as a result of the presence of mobile ions in the substance.
An ionic substance such as KBr when dissolved in water releases free ions which become charge carriers in solution hence the solution conducts electricity. Solid ionic substances such as solid KBr and solid baking soda do not conduct electricity because the ions are strongly bound to each other in the crystal lattice.
Molecular substances such as sugar and alcohol do not conduct electricity even in solution.
Na2CO3 reacts with dil.HCl to produce NaCl, H2O and CO2. If 21.2 g of pure Na2CO3 are added in a solution containing 21.9g HCl , a. Find the limiting reagent. (2) b. Calculate the number of moles of excess reagent left over.(2) c. Calculate the number of molecules of H2O formed.(1) d. Calculate volume of CO2 gas produced at 270C and 760mm Hg pressure.(2) e. Write significance of limiting reagent
Answer:
See explanation
Explanation:
Equation of the reaction;
Na2CO3(aq) + 2HCl(aq) -------> 2NaCl(aq) + H2O(l) + CO2(g)
Number of moles of Na2CO3 = 21.2g/106g/mol = 0.2 moles Na2CO3
Number of moles of HCl = 21.9g/36.5g/mol = 0.6 moles of HCl
1 mole of Na2CO3 reacts with 2 moles of HCl
0.2 moles of Na2CO3 reacts with 0.2 × 2/1 = 0.4 moles of HCl
Hence Na2CO3 is the limiting reactant
Since there is 0.6 moles of HCl present, the number of moles of excess reagent=
0.6 moles - 0.4 moles = 0.2 moles of HCl
1 mole of Na2CO3 forms 1 mole of water
0.2 moles of Na2CO3 forms 0.2 moles of water
Number of molecules of water formed = 0.2 moles × 6.02 × 10^23 = 1.2 × 10^23 molecules of water
1 mole of Na2CO3 yields 1 mole of CO2
0.2 moles of Na2CO3 yields 0.2 moles of CO2
1 mole of CO2 occupies 22.4 L
0.2 moles of CO2 occupies 0.2 × 22.4 = 4.48 L at STP
Hence;
V1=4.48 L
T1 = 273 K
P1= 760 mmHg
T2 = 27°C + 273 = 300 K
P2 = 760 mmHg
V2 =
P1V1/T1 = P2V2/T2
P1V1T2 = P2V2T1
V2 = P1V1T2/P2T1
V2 = 760 × 4.48 × 300/760 × 273
V2= 4.9 L
The limiting reactant is the reactant that determines the amount of product formed in a reaction. When the limiting reactant is exhausted, the reaction stops.
Suppose an enzyme and its substrate obey the lock and key model of enzyme catalysis. Which of the following would be true of the enzyme?
a. only one substrate could be converted to product by the enzyme
b. the active site of the enzyme must be rigid
c. the entire enzyme must be rigid
d. the active site of the enzyme must be flexible
e. the enzyme could bind different substrates if the substrates shared a common motif somewhere in their structures
Answer:
only one substrate could be converted to product by the enzyme
Explanation:
If an enzyme obeys the lock and key model, it then follows that the design of the enzyme is unique to a particular substrate.
Just as only the correct key can effectively fit into a lock, only the appropriate substrate whose design matches that of the enzyme can fit into the enzyme.
Owing to the lock and key model of enzyme activity, only one enzyme could interact with a substrate to yield particular product.
To insert a thermometer into an adapter, use ______ to prepare the thermometer. Then, hold the thermometer ______ the adapter and _____ the thermometer into the adapter.
Answer:
mineral oil; close to; slowly turn
Explanation:
Temperature can be defined as a measure of the degree of coldness or hotness of a physical object. It is measured with a thermometer and its units are Celsius (°C), Kelvin (K) and Fahrenheit (°F).
Generally, temperature measures the average kinetic energy of particles in a particular substance.
A thermometer can be defined as a device used for measuring the temperature (degree of hotness or coldness) of a body or substance is. It is a thin glass having a bulb on one of its end and typically contains either colored alcohol or mercury.
A thermometer adapter is used with a temperature probe in the distillation process, in order to determine readings.
To insert a thermometer into an adapter, use mineral oil to prepare or make suitable the thermometer. Then, hold the thermometer close to the adapter and slowly turn the thermometer into the adapter.
Consider an acid-base titration in which the base is dispensed from a burette into a flask containing an acid. If any drops of the base adhere to the inner walls of the flask, but do not actually mix with the solution, the calculated acid concentration would be
Answer:
Higher than the actual value
Explanation:
Titration is a volumetric process in which a known volume of solution is dispensed from a burette to react with a known volume of solution in a conical flask.
When acid-base titration is carried out in such a way that the base is in the burette and the acid is in the conical flask and drops of the base adhere to the inner walls of the flask, but do not actually mix with the solution, the calculated acid concentration would be higher than the actual value.
This is because;
From CA= CBVBnA/VAnB
When VB(volume of base) that reacted is lower than the actual volume recorded, then the calculated volume of CA(concentration of acid) is much higher than the actual value since drops of the base adhere to the inner walls of the flask.
How many doubtful digit(s) is/are allowed in any measured quantity?
(Only 3 choices.)
A.) 1
B.) 2
C.) zero
Answer:
zero
Explanation:
I I think one should be so accurate with measurements and experiments
How many molecules in each sample?
64.7 g N2
83 g CCl4
19 g C6H12O6
Answer:
1.39x10²⁴ molecules N₂.25x10²³ molecules CCl₄6.38x10²² molecules C₆H₁₂O₆Explanation:
First we convert the given masses into moles, using the compounds' respective molar mass:
64.7 g N₂ ÷ 28 g/mol = 2.31 mol N₂83 g CCl₄ ÷ 153.82 g/mol = 0.540 mol CCl₄19 g C₆H₁₂O₆ ÷ 180 g/mol = 0.106 mol C₆H₁₂O₆Then we multiply each amount by Avogadro's number, to calculate the number of molecules:
2.31 mol N₂ * 6.023x10²³ molecules/mol = 1.39x10²⁴ molecules0.540 mol CCl₄ * 6.023x10²³ molecules/mol = 3.25x10²³ molecules0.106 mol C₆H₁₂O₆ * 6.023x10²³ molecules/mol = 6.38x10²² molecules
Organic foods do not contain chemicals.
True
Or
False
Answer:
True
Explanation:
The word Organic refers to the methods used to cultivate and process farm agricultural products. Organic foods are edible and nutritious substances consumed (both plants and animals) that are free from the use of synthetics and chemicals. In plants, the include the use of organic manure that serves as fertilizers and carrying out the weeding process by hand weeding. In animals, diseases can be prevented by maintaining a clean house or rotational grazing.
The benefit of organic foods are to produce food substances with no chemical substances.
A compound was analyzed and found to contain 76.57% carbon, 6.43% hydrogen, and 17.00% oxygen by mass. Calculate the empirical formula of the compound. If the molar mass of the compound is 94.11 g/mol, what is the molecular formula of the compound?
A second compound is composed of 53.30% Carbon 11.19% Hydrogen and 35.51% Oxygen by mass.Please Calculate the empirical formula of the compound of the molar mass of the compound is 90.12g/mol, what is the molecular formula for that compound?
Answer:
See explanation
Explanation:
First we divide the percentage by mass of each element by it's relative atomic mass then we divide the quotients obtained by the lowest ratio obtained in the first step.
C- 76.57/12, H= 6.43/1, O = 17.00/16
C- 6.38/1.06, H= 6.43/1.06, O= 1.06/1.06
C- 6, H- 6, O- 1
Empirical formula: C6H6O
[(12 ×6) + (6 × 1) + (16 × 1)]n=94.11
[72 + 6 +16]n = 94.11
n = 94.11/94
n= 1
Molecular formula = C6H6O
2)
C- 53.30/12, H- 11.19/1, O- 35.51/16
C- 4.44/2.22, H- 11.19/2.22, O- 2.22/2.22
C- 2, H- 5, O- 1
Empirical formula: C2H5O
[(2×12) + (5× 1) + (1×16)]n = 90.12
[24 + 5 + 16] n = 90.12
n= 90.12/45
n= 2
Molecular formula = C4H10O2
When Hg2+ concentration is 6.35x10^-4 M, the observed cell potential at 298K for an electrochemical cell with the following reaction is 1.499V. What is the Cr3+ concentration?
3H^2+ (aq) + 2Cr(s)= 3Hg(l) + 2Cr^3+(aq)
Answer:
10.5 × 10^5 M
Explanation:
E°cell = E°cathode - E°anode
E°cell = 0.85 - (-0.74) = 1.59 V
From Nernst's equation;
Ecell = E°cell - 0.0592/n log Q
1.499 = 1.59 - 0.0592/6 log [Cr^3+]/6.35x10^-4
1.499 - 1.59 = - 0.0592/6 log [Cr^3+]/6.35x10^-4
-0.091 = -0.00987 log [Cr^3+]/6.35x10^-4
-0.091/ -0.00987 = log [Cr^3+]/6.35x10^-4
9.22 = log [Cr^3+]/6.35x10^-4
Antilog (9.22) = [Cr^3+]/6.35x10^-4
1.66 × 10^9 = [Cr^3+]/6.35x10^-4
[Cr^3+] = 1.66 × 10^9 × 6.35x10^-4
[Cr^3+] = 10.5 × 10^5 M
Which event would be impossible to explain by using John Dalton's model of the atom?
Answer:
That is, the atom is a solid and indivisible mass. However, the fenomenom by which an iron atom emits particles when it is struck by light (known as the photoelectric effect) can not be explaind by this indivisible atom model.
Explain why the balls representing fluorine (teal) and hydrogen (white) have only one peg, while carbon (black) has four.
Answer:
Hydrogen and fluorine form only one bond while carbon forms four bonds to other atoms.
Explanation:
This question brings us to the idea of valency. Fluorine is univalent while carbon is tetravalent.
Univalent means that fluorine can only form one bond to hydrogen while carbon forms as much as four bonds because it is tetravalent.
Hence fluorine and hydrogen have only one peg while carbon has four.