The majority of metals are found in ores.
But a few such as copper, gold, platinum, and silver frequently occur in the free state because they do not readily react with other elements.
A mixture is -
A. a pure substance made through chemical processes
B. a pure substance made through physical processes
C.
an impure substance made through chemical processes
D.
an impure substance made through physical processes
Answer:
C
Explanation:
an impure substance made through chemical process
What is the
energy
2) The energy transition from n = 1 →n= 3 in hydrogen is 12.09 eV (1.6022 X 10J= 1 eV)-
of light emitted from n = 3 →n=1?
E e fiz
Answer:
energy is the ability to do work
atomaticity of chlorine 1) 2, 2)1, 3) 32 , 4) 4.
Answer:
ATOMICITY OF CHLORINE IS 2Explanation:
Atomicity is defined as the total number of atoms present in a molecule.
Given the amount of camphor (200mg) we are using in this experiment, please determine how many mg of sodium borohydride to use in this reaction. We would like you to use 5.2 molar equivalents of this reagent. This means 5.2 times the mmol of camphor we are using. As an example: for 110.0 mg of camphor,142 mg of NaBH4 would be used (see if you can confirm this result). For complete credit, your work needs to be clearly drawn out!
Answer:
Explanation:
From the given information:
Camphor may be reduced as readily in the presence of sodium borohydride(NaHB4). The resulting compound which is stereoselective requires 1 mole of sodium borohydride (NaHB4) to reduce 1 mole of camphor in this reaction. The reaction is shown below.
Through the reduction process of camphor, the reducing agent can reach the carbonyl face with a one-carbon linkage. The product stereoisomer is known as borneol.
If the molecular weight of camphor = 152.24 g/mol
and it mass = 200 mg
The its no of moles = 200 mg/ 152.24 g/mol
= 1.3137 mmol
Now the amount of the required mmol for NaBH4 to be consumed in the reaction = 5.2 × 1.3137 mmol
= 6.831 mmol
since the molar mass of NaBH4 = 37.83 g/mol
Then, using the same formula:
No of moles = mass/molar mass
mass = No of moles × molar mass
mass = 6.831 mmol × 37.83 g/mol
mass of NaBH4 used = 258.42 mg
ype the correct answer in the box.
Calculate the density of the substance.
A sample of a substance has a mass of 4.2 grams and a volume of 6 milliliters. The density of this substance is grams/milliliter.
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Explanation:
here is your answer. Hope it helps
A cylinder contains 3.1 L of oxygen at 300 K and 2.7 atm. The gas is heated, causing a piston in the cylinder to move outward. The heating causes the temperature to rise to 610 K and the volume of the cylinder to increase to 9.4 L.
How many moles of gas are in the cylinder?
Express your answer using two significant figures.
Answer: The moles of gas present in the cylinder is 0.34 moles.
Explanation:
Given: [tex]P_{1}[/tex] = 2.7 atm, [tex]V_{1}[/tex] = 3.1 L, [tex]T_{1}[/tex] = 300 K
[tex]P_{2}[/tex] = ?, [tex]V_{2}[/tex] = 9.4 L, [tex]T_{2}[/tex] = 610 K
Formula used to calculate the final temperature is as follows.
[tex]\frac{P_{1}V_{1}}{T_{1}} = \frac{P_{2}V_{2}}{T_{2}}[/tex]
Substitute the values into above formula as follows.
[tex]\frac{P_{1}V_{1}}{T_{1}} = \frac{P_{2}V_{2}}{T_{2}}\\\frac{2.7 atm \times 3.1 L}{300 K} = \frac{P_{2} \times 9.4 L}{610 K}\\P_{2} = \frac{5105.7}{2820} atm\\= 1.81 atm[/tex]
Now, moles present upon heating the cylinder are as follows.
[tex]P_{2}V_{2} = n_{2}RT_{2}\\1.81 atm \times 9.4 L = n_{2} \times 0.0821 L atm/mol K \times 610 K\\n_{2} = \frac{17.014}{50.081} mol\\= 0.34 mol[/tex]
Thus, we can conclude that moles of gas present in the cylinder is 0.34 moles.
Nitrogen monoxide and ozone react to form nitrogen dioxide and oxygen, like this:
NO(g) + O3 → NO2 + O2
The reaction is exothermic. Suppose a mixture of NO, O3 NO and O2 has come to equilibrium in a closed reaction vessel. Predict the change.
Answer:
The pressure of O2 will increase. Shift to the right.
The pressure of O3 will increase . Dhift to the left
Explanation:
The perturbations are:
The temperature is lowered. The pressure of O2 will
The temperature is raised. The pressure of O3 will:
We can Apply LeCh's principle and see the heat, ΔH, as a product of the reaction:
NO(g) + O3(g) → NO2(g) + O2(g) + ΔH
If temperature is lowered, the system will shift to the right in order to produce more heat doing:
The pressure of O2 will increase
In the other way, if temperature is raised, the system will shift to the left in order to decrease the amount of heat produced.
The pressure of O3 will increase
Calculate the osmotic pressure of 5.0g of sucrose ssolution in 1L. Answer should be in Torr
Answer: The osmotic pressure of 5.0g of sucrose solution in 1 L is 271.32 torr.
Explanation:
Given: Mass = 5.0 g
Volume = 1 L
Molar mass of sucrose = 342.3 g/mol
Moles are the mass of a substance divided by its molar mass. So, moles of sucrose are calculated as follows.
[tex]Moles = \frac{mass}{molarmass}\\= \frac{5.0 g}{342.3 g/mol}\\= 0.0146 mol[/tex]
Hence, concentration of sucrose is calculated as follows.
[tex]Concentration = \frac{moles}{Volume (in L)}\\= \frac{0.0146 mol}{1 L}\\= 0.0146 M[/tex]
Formula used to calculate osmotic pressure is as follows.
[tex]\pi = CRT[/tex]
where,
[tex]\pi[/tex] = osmotic pressure
C = concentration
R = gas constant = 0.0821 L atm/mol K
T = temperature
Substitute the values into above formula as follows.
[tex]\pi = CRT\\= 0.0146 \times 0.0821 L atm/mol K \times 298 K\\= 0.357 atm (1 atm = 760 torr)\\= 271.32 torr[/tex]
Thus, we can conclude that the osmotic pressure of 5.0g of sucrose solution in 1 L is 271.32 torr.
what following oxide react with both acids and bases to form salts.
Answer:
mainly metal oxide use to react with both acid and bases to form salts such as zinc, aluminum etc.
At 298 K, AHO = -1652 kJ/mol and ASO = 0.097 kJ/(K•mol). What is the Gibbs
free energy of the reaction?
Based on the calculations, the Gibbs's free energy for this chemical reaction is equal to -1,680.906 kJ/mol.
Given the following data:
Enthalpy of reaction (ΔH°) = -1652 kJ/mol.Temperature = 298 K.Entropy of reaction (ΔS°) = 0.097 kJ/mol.What is Gibbs's free energy?Gibbs's free energy simply refers to the quantity of energy that is associated with a particular chemical reaction.
Mathematically, the Gibbs's free energy for this chemical reaction can be calculated by using this formula:
ΔG° = ΔH° - ΔS°
Substituting the given parameters into the formula, we have;
ΔG° = -1652 × 10³ - (298 × 0.097)
ΔG° = -1652 × 10³ - 28.906
ΔG° = -1,680.906 kJ/mol.
Read more on Gibbs's free energy here: brainly.com/question/18752494
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Draw a Lewis structure for thiocyanic acid, HSCN, adding charges and lone electron pairs to the appropriate atoms.
Answer:
See explanation and image attached
Explanation:
Thiocyanic acid is made made up of hydrogen, sulphur, carbon and nitrogen atoms. Carbon is the central atom in the molecule.
The molecule has a total of sixteen valence electrons as shown in the image attached. There are no formal charges in the structure of the molecule as shown.
The molecule is linear in shape.
Calculate the average atomic mass for X
Answer:
39.0229 amu
Explanation:
Hello there!
In this case, according to given information, the idea here is to multiply the percent abundance by the mass number of each isotope and then add them all together as shown below:
[tex]=0.0967*38+0.7868*39+0.1134*40+0.0031*41\\\\=3.6746+30.6852+4.536+0.1271\\\\=39.0229amu[/tex]
Regards!
Which is used to measure conc. HCl for preparation of 0.1M HCl solution?
a. Volumetric flask c. Measuring cylinder
b. Pipette d. Wash bottle
Answer:
option a
hope helps you
have a great day
We can use bond-line formulas to represent alkenes in much the same way that we use them to represent alkanes. Consider the following alkene: h5ch5e4 How many carbon atoms are sp2−hybridized in this alkene?
Answer:
2
Explanation:
The number of carbon atoms that are sp²-hybridized in this alkene is 2
Because all the single bonded carbon atoms in the alkene are sp²-hybridized
There are three(3) single formed via sp² orbitals and one ( 1 ) PI bond formed via Pure-P-orbital
attached below is the some part of the solution
if a=1/2(a+b)h,express a in terms of A,b and h. pls solve with step by step
Answer:
[tex] a = \frac {2A - bh}{h} [/tex]
Explanation:
Given the following mathematical expression;
A = ½(a + b)h
To make a the subject of formula (express a in terms of A, b and h);
First of all, we would cross-multiply;
2A = (a + b)h
Opening the bracket, we have;
2A = ah + bh
Rearranging the mathematical expression, we have;
ah = 2A - bh
[tex] a = \frac {2A - bh}{h} [/tex]
Predict the reactants of this chemical reaction. That is, fill in the left side of the chemical equation. Be sure the equation you submit is balanced. (You can edit both sides of the equation to balance it, if you need to.)
______________ → BaBr2 + H2O
Answer:
Ba(OH)₂ + 2 HBr ⇒ BaBr₂ + 2 H₂O
Explanation:
We have the products of a reaction and we have to predict the reactants. Since the products are binary salt and water, this must be a neutralization reaction. In neutralizations, acids react with bases. The acid that gives place to Br⁻ is HBr, while the base the gives place to Ba²⁺ is Ba(OH)₂. The balanced chemical equation is:
Ba(OH)₂ + 2 HBr ⇒ BaBr₂ + 2 H₂O
A chemist combines 33 g of methane with 289 g of oxygen to from 189 g of carbon dioxide and 30 g of water. Determine if the results of the following word problem adheres to the Law of Conservation of Mass.
Answer:
The correct answer is - no not adhere to the law of mass conservation.
Explanation:
According to the law of mass conservation in an isolated system, the mass can not be created or destroyed and in a chemical or physical change, the mass of products should be always equal to the mass of reactants.
On the basis of the law the mass of the chemical reaction-
Mass of products = mass of reactants
33 g of methane + 289g of oxygen = 189g of carbon dioxide + 30g of water
322g ≠ 219 g
which means this reaction does not adhere to the law of conservation.
The time required to pass one Faraday of electricity through a solution with a current of 0.3A is
Answer:
89.35 hour
Explanation:
Recall :
Charge on 1 electron = 1.6 × 10^-19 C
1 mole contains = 6.023 × 10^23
Therefore, the charge on 1 mole of electron will be :
Charge per electron × 1 mole :
(1.6 × 10^-19) * (6.023 * 10^23) = 96500 C = 1 Farad
1 Farad = 96500 C
Using the formula :
Q = Current(I) * time(t)
Q = I*t
t = Q/I
Current, I = 0.3 A
t = 96500 / 0.3
t = 321666.66 second
t = 321666.66 / 3600 = 89.35 hour
If mercury barometer is replaced by water barometer, height of water column
i. will be less than that of Hg Column
ii. will be greater than that of Hg column iii. will be equal to that of Hg column
iv. will be none of these
Answer:
answer is first one 1 will be less then that of hg coloumn
A gas mixture is made by combining 8.7 g each of Ar, Ne, and an unknown diatomic gas. At STP, the mixture occupies a volume of 17.28 L. What is the molar mass of the unknown gas
Answer: Molar mass of the unknown gas is 73.153 g/mol.
Explanation:
Given: Mass of each gas = 8.7 g
Volume = 17.28 L
Let us assume that the molar mass of gas is m g/mol.
Molar mass of Ar is 40 g/mol and Ne is 20 g/mol.
Hence, total moles of each gas are as follows.
[tex](\frac{8.7}{40} + \frac{8.7}{20} + \frac{8.7}{m}) mol[/tex]
At STP, the total volume of these gases is as follows.
[tex](\frac{8.7}{40} + \frac{8.7}{20} + \frac{8.7}{m}) mol \times 22.4 L = 17.28 L\\(\frac{8.7}{40} + \frac{8.7}{20})22.4 L + \frac{8.7}{m} \times 22.4 L = 17.28 L\\14.616 + \frac{8.7}{m} \times 22.4 L = 17.28 L\\\frac{8.7}{m} \times 22.4 L = (17.28 L - 14.616)\\\frac{8.7}{m} \times 22.4 L = 2.664 \\m = 73.153 g/mol[/tex]
Thus, we can conclude that molar mass of the unknown gas is 73.153 g/mol.
What should be done if a spectrophotometer reports an absorbance that is too high? Select one: Reposition the cuvette in the spectrophotometer. Pour out half the volume of the sample. Restart the spectrophotometer and try again. Dilute the sample. g
Answer:
The sample should be diluted
Explanation:
According to Beer Lambert's law, the absorbance of a sample depends on the concentration of the sample.
Hence, if the concentration of the sample is very high, the spectrophotometer will also report a very high value of absorbance.
When this is the case, the sample should simply be diluted and the readings are taken again using the spectrophotometer.
Answer True or False for each of the following statements. (a) The carburization surface was maintained at slightly less than 0.25 wt% carbon for each specimen. (b) Comparing the finished specimens at a depth of 0.20 mm, specimen A features the lowest carbon concentration. (c) Comparing the finished specimens as a whole, specimen D features the lowest overall amount of carbon.
Answer:
verdadero/a
falso/b
verdadero/c
Explanation:
Calculate the volume in liters of a 1.60 mol/L sodium nitrate solution that contains of sodium nitrate . Round your answer to significant digits.
Answer:
1.5L of NaNO3 must be present
Explanation:
That contains 200g of sodium nitrate. Round to 2 significant digits
To solve this question we need to convert the mass of NaNO3 to moles using its molar mass (85g/mol). With the moles and the molar concentration we can find the volume in liters of the solution:
Moles NaNO3:
200g * (1mol / 85g) = 2.353 moles NaNO3
Volume:
2.353 moles NaNO3 * (1L / 1.60moles) =
1.5L of NaNO3 must be presentthe question is in the attachment
Answer:
About redox reaction which of the given statements are true?
Explanation:
Redox reaction is the one in which both oxidation and reduction reactions take place simultaneously.
For example:
[tex]C(s)+O_2(g)->CO_2(g)[/tex]
In this reaction, carbon undergoes oxidation and oxygen undergoes reduction simultaneously.
During this reaction, mutual exchange of electrosn take place between the oxidant and the reductant.
Among the given options,
Option B. electrons are transferred
and
option C.They include both oxidation and reduction takes place are the correct answers.
Give the number of lone pairs around the central atom and the molecular geometry of SCl2. Multiple Choice 3 lone pairs, linear 1 lone pair, bent 3 lone pairs, bent 0 lone pairs, linear 2 lone pairs, bent
Answer:
2 lone pairs, bent
Explanation:
According to the Valence Shell Electron Pair Repulsion Theory, the number of electron pairs on the valence shell of the central atom in a molecule influences the shape of the molecule.
The presence of lone pairs on the valence shell of the central atom causes the observed molecular geometry to deviate from the ideal geometry predicted on the basis of the valence shell electron pair repulsion theory.
SCl2 has four regions of electron density. This means that its electron domain geometry is tetrahedral. However, there are two lone pairs on the valence shell of the central atom hence the observed molecular geometry is bent.
The products obtained from hydroboration-oxidation of cis-2-butene are identical to the products obtained from hydroboration-oxidation of trans-2-butene. Draw the products and explain why the configuration of the starting alkene is not relevant in this case.
Answer:
a) Attached below
b) The presence of racemic mixture found as product in both cases shows that products are identical ( i.e. they have same configuration
Explanation:
Diagrams of the products obtained from hydroboration-oxidation of cis-2-butene , hydroboration-oxidation of trans-2-butene.
attached below
The presence of racemic mixture found as product in both cases shows that products are identical ( i.e. they have same configuration )
how many lone pair electrons are on the central oxygen atom in the Lewis structure for dinitrogen pentoxide 9
Answer:
Two
Explanation:
Lone pairs are electron pairs on an atom that resides only with one of the atoms in a molecule.
Dinitrogen pentaoxide is shown in the image attached. There are five oxygen atoms and two nitrogen atoms in the molecule. The molecule has a total of 40 valence electrons.
There are two electrons present on the central oxygen atom in the Lewis structure of dinitrogen pentaoxide as shown in the image attached.
the ability of organism to sense changes in its body is an example of
Answer:
the ability of organism to sense changes in its body is an example of responsiveness.Hope it is helpful to you
What effect does hybridization have on chemical bond
Determine if the following statement is true or false, and why. “A hypothesis can be proven true.”
Answer:
True
Explanation:
A hypothesis can be proven true through experimentation. For example, if you hypothesize that a balloon with helium will float in the air, and then you test this and the balloon floats, you have just proven that your original hypothesis is true.
