What element has the same number of valence electrons as sulfur?
A physical change does not involve a change in the substance’s chemical identity. Which of these statements describes a physical change?
Group of answer choices
A banana starts to smell as it ripens.
Onions taste sweeter after being cooked.
Aluminum cans get crushed before recycling.
Copper turns green when exposed to air.
Answer: the answer is C Aluminum cans get crushed before recycling.
Explanation:
Answer:
it will option C because it had no change in chemical reaction
Classify each of the following compounds as a strong acid, weak acid, strong base, or weak base, and write the Ka expression for any weak acid or weak base:
1. [ Select ] ["strong base", "weak base", "strong acid", "weak acid"] LiOH
2. [ Select ] ["weak acid", "strong acid", "strong base", "weak base"] HF
3. [ Select ] ["strong acid", "weak acid", "strong base", "weak base"] HCl
4. [ Select ] ["weak base", "strong base", "weak acid", "strong acid"] NH3
Ka expression: [ Select ] ["[H+][F-] / [HF]", "[Li+][OH-]/ [LiOH]", "[H+][Cl-} / [HCl]", "[NH4+] / [NH3]", "[HF] / [H+][F-}", "[LiOH] / [Li+][OH-]", "[HCl] / [H+][Cl-}", "none"]
Calculate the concentration of OHLaTeX: -? in a solution that has a concentration of H+ = 7 x 10LaTeX: -?6 M at 25°C. Multiply the answer you get by 1010 and enter that into the field to 2 decimal places.
Answer:
See explanation below
Explanation:
There are several ways to know if an acid or base is strong. One method is calculating the pH. If the pH is really low, is a strong acid, and if it's really high is a strong base.
However we do not have a pH value here.
The other method is using bronsted - lowry theory. If an acid is strong, then his conjugate base is weak. Same thing with the bases.
Now, Looking at the 4 compounds, we can say that only two of them is weak and the other two are strong compounds. Let's see:
LiOH ---> Strong. If you try to dissociate :
LiOH ------> Li⁺ + OH⁻ The Li⁺ is a weak conjugate acid.
HF -----> Weak
HF --------> H⁺ + F⁻ The Fluorine is a relatively strong conjugate base.
HCl -----> Strong
This is actually one of the strongest acid.
NH₃ ------> Weak
Now writting the Ka and Kb expressions:
Ka = [H⁺] [F⁻] / [HF]
Kb = [NH₄⁺] [OH⁻] / [NH₃]
Finally, to calculate the [OH⁻] we need to use the following expression:
Kw = [H⁻] [OH⁻]
Solving for [OH⁻] we have:
[OH⁻] = Kw / [H⁺]
Remember that the value of Kw is 1x10⁻¹⁴. So replacing:
[OH⁻] = 1x10⁻¹⁴ / 7x10⁻⁶
[OH⁻] = 1.43x10⁻⁹ M
And now, multiplying by 10¹⁰ we have:
[OH⁻] = 1.429x10⁻⁹ * 1x10¹⁰
[OH⁻] = 14.29Hope this helps
Strong acids and bases are those which completely ionized in body fluid, and weak acids and bases are those who does not completely ionized in body fluid.
Ka expression is used to differentiate between strong and weak acids.
Which are strong acids and base and weak acids and bases?LiOH - strong baseHF - weak acidHCl - strong acidNH3 - weak baseWhat are the Ka expression of the following?Weak acid – HF[tex]\bold{\dfrac{[H+][F-]}{[HF]}}[/tex]
Weak base – NH3[tex]\bold{\dfrac{[NH_4^+] [OH^-]}{[NH_3]} }[/tex]
Calculate the concentration of OH?Given, [tex]\bold{ [H^+]=1\times10^-^6\; at \;25^oC}[/tex]
We know, [tex]\bold{ [H^+]\times[OH^-]=1\times10^-^6\; at \;25^oC}[/tex]
[tex]\bold{[OH^-]=\dfrac{1\times10^-^1^4}{6.2\times10^-^6} = 1.43\times10^-^9}[/tex]
Now, multiplying the value by [tex]10^1^0[/tex]
[tex]\bold{( 1.429\times10^-^9) \times 1\times10^1^0= 14.29}[/tex]
Thus, the value is 14.29.
Learn more about acid and base, here:
https://brainly.com/question/10468518
My labmate discovered a new compound and wanted to try to determine what it could be. We noticed that when mixed with an acid, it formed a white solid. What type of chemical reaction did the new chemical just undergo?
Answer:
it went under the process known as crystalization
Explanation:
am a chemist
there is concern in health-related government agencies that the american diet contains too much meat, and numerous recommendations have been made urging people to consume more fruit and vegetables. one of the richest sources of vegetable protein is soy, available in many forms. among these is soybean curd, or tofu, which is a staple of many asian diets. chemists have isolated an anticancer agent called genistein from tofu, which may explain the much lower incidence of cancer among people in the far east. a valid lewis structure for genistein is
Answer:
Explanation:
The aim of this question is to draw the structure of genistein and determine the number of atoms with sp² hybridization in the molecule.
From the image below, we will see the lewis structure of genistein. From the image, the blue asterisk atoms are sp² hybridized and the red marked atoms are sp³ hybridized.
We will also notice that all the carbon atoms contain 3 σ-bonds with no lone pair of electrons.
Using the knowledge of Valence shell electron repulsion theory (VSEPR), the above-mentioned carbon atom is said to be sp²hybridized.
Also, the oxygen atoms which are doubly bounded contains 1 σ-bond and 2 lone pair electrons. These oxygen atoms are also sp² hybridized.
Finally, the singly bonded oxygen atom is composed of 2 σ-bonds and 2 lone pair electrons. This makes it to be sp³ hybridized.
Altogether, we have a total of 16 sp² hybridized atoms and 4 sp³ hybridized atoms.
When Elsa freezes things, is it an example of an exothermic or
endothermic reaction? Explain.
Answer:
endothermic reaction
Explanation:
When Elsa from Frozen freezes things, it is an example of an endothermic chemical reaction.
An endothermic involves a reaction in which heat is absorbed from the surrounding. Hence the surrounding becomes colder at the end of the the change.
So, Elsa draws heat from the environment and this causes the environment to be colder and things that are in contact with her.
Arrange the following elements in order of increasing (from smallest to largest) atomic size: K, O, Cs, Se. Explain the reasoning behind your chosen order. Do not simply restate the trend, but rather explain why the trend exists.
What is the total amount of heat released in kilojoules when 112.0 g water at 50.0∘C cools to form ice at −45.0∘C? Use the following values for calculations, as needed.
Properties of Water−−−−−−−−−−−−−−−−−−Specific Heats(∘C)gas=1.84 J/g∘Cliquid=4.184 J/g∘Csolid=2.09 J/g∘C
Heat of VaporizationΔHvap=40.7 kJ/molHeat of FusionΔHfus=6.01 kJ/mol
Answer:
Q = 44.5 kJ
Explanation:
Given that,
Mass of water, m = 112 g
Water at 50.0°C cools to form ice at −45.0°C
We need to find the total amount of heat released. The formula for heat released is given by :
[tex]Q=mc\Delta T[/tex]
c is the specific heat of water, c = 4.184 J/g°C
So,
[tex]Q=112\times 4.184 \times (-45-50)\\\\Q=-44517.76\ J[/tex]
or
Q = -44.5 kJ
So, 44.5 kJ of heat is released.
A 32.60 g sample of a solid is placed in a flask. Toluene, in which the solid is insoluble, is added to the flask so that the total volume of solid and liquid together is 51.00 mL . The solid and toluene together weigh 58.86 g . The density of toluene at the temperature of the experiment is 0.864 g/mL. What is the density of the solid?
Answer:
0.864 g/mL.
Explanation:
I hope this helps u! also have a great rest of your day!
LaKeisha is measuring the density of a solid piece of metal using the graduated cylinder method. She initially measures a volume of water in the cylinder to be 3.28 mL. After placing the metal into the graduated cylinder, the new volume was 8.72 mL. The mass of the metal was 42.26 g on a top loading balance.
Required:
What is the density of the metal calculated to the correct number of significant figures?
Answer: 7.77 g/ml
Explanation:
Volume of cylinder with only water = 3.28 mL
Volume of cylinder with water and metal = 8.72 mL
Volume of metal = (Volume of cylinder with water and metal ) -(Volume of cylinder with only water)
=8.72-3.28
=5.44 ml
Mass of metal = 42.26 g
Formula of Density = [tex]\dfrac{\text{Mass}}{\text{Volume}}[/tex]
i.e. the density of the metal = [tex]\dfrac{42.26}{5.44}\approx7.77\text{ g/ml}[/tex]
Hence, the density of metal = 7.77 g/ml
Were any of your substances difficult to identify as polar, nonpolar, or ionic? Explain.
Answer:
See explanation
Explanation:
A substance is classified as polar, nonpolar or ionic based on its behavior.
For the substances identified, there was no difficult in identifying each as polar, nonpolar, or ionic because since it was quite to easy identify where each belongs by looking out for whether it mixes or dissolves in our experiment.
Every substance in the experiment either mixed or dissolved during the experiment.
What effect is climate change having on the amount of water in liquid, solid, and gas forms on Earth?
Which of the following has the largest atomic radius?
Answer:
b
Explanation:
What is the main type of energy conversion that happens to a ball thrown in
the air as it goes up?
A. Kinetic energy to gravitational potential energy
B. Gravitational potential energy to kinetic energy
C. Chemical potential energy to kinetic energy
D. Kinetic energy to chemical potential energy
0
Which is not one of Earth's layers?
A А
crust
B)
inner core
mantle
D
ocean
The ocean is not a part of Earth's layers.
Answer:
Ocean
Explanation:
Part I: SP3 Hybridization: B: Ethane Distance between C-C in ethane: ________________ Distance between H atoms in eclipsed conformation: ________________ Distance between H atoms in staggered conformation: ________________ Which is more stable (circle one): STAGGERED or ECLIPSED
Answer:
Distance between C-C in ethane- 1.54 Å
Distance between H atoms in eclipsed conformation-2.3 Å
Distance between H atoms in staggered conformation- 2.5 Å
Staggered conformation is more stable
Explanation:
The staggered conformation of ethane can be demonstrated as the most stable of conformation of ethane, because the angles between Carbon-Hydrogen bonds in both the front and back carbon atoms are maximized. This now minimizes the energy of this conformation compared to the eclipsed conformation.
Considering the eclipsed conformation, it is obvious that the electron densities on Carbon-Hydrogen bonds come very close together thereby bringing two C-H bonds into a dihedral angle of almost zero degrees. This causes their electron clouds to experience strong repulsion, thereby raising the molecules's total energy.
PLEASE HELPP!
Question #9
Long Text (essay)
Summarize the arguments both for and against allowing genetically altered meats into the United States.
B
1
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I
© 2013 Glynlyon, Inc.
< PREV
Answer:
The arguments both for and against allowing genetically altered meats into the United States is explained below in details.
Explanation:
Arguments for and against genetically altered meats:
Supply the Society. By 2050, the world's inhabitants are supposed to increase from today's 7 billion to way beyond 9 billion.ENVIRONMENTAL RISK. STRONGER CROPS = LESS PESTICIDES. REMEMBER WHEN CIGARETTES WERE 'HARMLESS'? TAMPERING FOR TASTE. ...BIG BUSINESS EATS SMALL FARMERS. ENHANCED HEALTH. NOTHING TASTES BETTER THAN NATURE.Answer:
The arguments both for and against allowing genetically altered meats into the United States is explained below in details.
Explanation:
Arguments for and against genetically altered meats:
Supply the Society. By 2050, the world's inhabitants are supposed to increase from today's 7 billion to way beyond 9 billion.
ENVIRONMENTAL RISK.
STRONGER CROPS = LESS PESTICIDES.
REMEMBER WHEN CIGARETTES WERE 'HARMLESS'?
TAMPERING FOR TASTE. ...
BIG BUSINESS EATS SMALL FARMERS.
ENHANCED HEALTH.
NOTHING TASTES BETTER THAN NATURE.
Explanation:
A cylinder containing CH4, C2H6, and N2 has to be prepared in which the ratio of the moles of CH4 to C2H6 is 1.3 to 1. Available are (1) a cylinder containing a mixture of 70% N2 and 30% CH4, (2) a cylinder containing a mixture of 90% N2 and 10% C2H6, and a cylinder of pure N2. Determine the proportions in which the respective gases from each cylinder should be used
Answer:
The proportions in which the respective gases from each cylinder should be used; C1 : C2 : C3 = 1 : 2.308 : C3
Explanation:
Given that;
CH4 to C2H6 = 1.3 to 1
Cylinder 1 = 70% N2 and 30% CH3
Cylinder 2 = 90% N2 and 10% C2H6
Cylinder 3 = ( pure N2 ) = 100% N2
CH4 to C2H6 = (1.3 to 1)
we have CH4 and C2H6 in cylinder 1 and 2 only
we only have balance material in c1 and c2
Now, Let x be from cylinder and ( 1-x ) be from cylinder 2
so, 30x / 10( 1-x ) = 1.3 / 1
30x = (10 - 10x)1.3
30x = 13 - 13x
30x + 13x = 13
x = 13/43
x = 0.3023
Also, ( 1-x ) = ( 1 - 0.3023) = 0.6977
so
C1/C2 = 0.3023/0.6977 = 1 / 2.308 while c3 can be anything;
Therefore, C1 : C2 : C3 = 1 : 2.308 : C3
16. Using the average atomic masses given in the inside front cover of this book, calculate the indicated quantities.
d. the number of moles of cobalt represented by 5.99 x 1021 cobalt atoms e. the mass of 4.23 mol of cobalt
f. the number of cobalt atoms in 4.23 mol of cobalt
g. the number of cobalt atoms in 4.23 g of cobalt
Answer:
d. 9.95 × 10⁻³ mol
e. 249 g
f. 2.55 × 10²⁴ atoms
g. 4.32 × 10²² atoms
Explanation:
d. the number of moles of cobalt represented by 5.99 x 10²¹ cobalt atoms
We will use Avogadro's number: there are 6.02 × 10²³ atoms of cobalt in 1 mole of atoms of cobalt.
5.99 x 10²¹ atoms × 1 mol/6.02 × 10²³ atoms = 9.95 × 10⁻³ mol
e. the mass of 4.23 mol of cobalt
The molar mass of cobalt is 58.93 g/mol.
4.23 mol × 58.93 g/mol = 249 g
f. the number of cobalt atoms in 4.23 mol of cobalt
We will use Avogadro's number: there are 6.02 × 10²³ atoms of cobalt in 1 mole of atoms of cobalt.
4.23 mol × 6.02 × 10²³ atoms/1 mol = 2.55 × 10²⁴ atoms
g. the number of cobalt atoms in 4.23 g of cobalt
First, we will calculate the moles of cobalt using the molar mass of cobalt.
4.23 g × 1 mol/58.93 g = 0.0718 mol
Then, we will calculate the number of cobalt atoms using Avogadro's number.
0.0718 mol × 6.02 × 10²³ atoms/1 mol = 4.32 × 10²² atoms
I need a help please!
Answer:
B. KBr + F2
Explanation:
In displacement reactions (reactions in which an element replaces another element in a compound) like these, reactive element displaces the less reactive element.
A. NaBr + I2
This reaction will not occur because Iodine is not able to displace bromine from the compound.
B. KBr + F2
This reaction will occur because flourine is more reactive and hence is able to displace bromine from the reaction.
C. LiF + Cl2
This reaction will not occur because chlorine is not able to displace flourine from the compound.
D. NaCl + I2
This reaction will not occur because Iodine is not able to displace Chlorine from the compound.
PLEASE HELP BRAINLIEST AND 15 points.
1. Which substance is nonvolatile ?
(1.5 Points)
Substance B, boiling point of 105 °C
Substance C, boiling point of 25 °C
Substance A, boiling point of 75 °C
Substance d, boiling point of 45 °C
Answer:
Substance B, boiling point of 105 °C
Explanation:
Non volatile substances have high boiling points
The change in entropy is related to the change in the number of moles of gas molecules. Determine the change in moles of gas for each of the reactions and decide if the entropy increases decreases or has little to no change.
The given question is incomplete. The complete question is:
The change in entropy is related to the change in the number of moles of gas molecules. Determine the change in moles of gas for each of the reactions and decide if the entropy increases decreases or has little to no change:
A. [tex]K(s)+O_2(g)\rightarrow KO_2(s)[/tex]
B. [tex]CO(g)+3H_2(g)\rightarrow CH_4(g)+H_2O(g)[/tex]
C. [tex]CH_4(g)+2O_2(g)\rightarrow CO_2(g)+2H_2O(g)[/tex]
D. [tex]N_2O_2(g)\rightarrow 2NO(g)+O_2(g)[/tex]
Answer: A. [tex]K(s)+O_2(g)\rightarrow KO_2(s)[/tex] : decreases
B. [tex]CO(g)+3H_2(g)\rightarrow CH_4(g)+H_2(g)[/tex] : decreases
C. [tex]CH_4(g)+2O_2(g)\rightarrow CO_2(g)+2H_2O(g)[/tex]: no change
D. [tex]N_2O_2(g)\rightarrow 2NO(g)+O_2(g)[/tex] : increases
Explanation:
Entropy is defined as the randomness of the system.
Entropy is said to increase when the randomness of the system increase, is said to decrease when the randomness of the system decrease and is said to have no change when the randomness remains same.
In reaction [tex]K(s)+O_2(g)\rightarrow KO_2(s)[/tex], as gaseous reactant is changed to solid product, entropy decreases.
In reaction [tex]CO(g)+3H_2(g)\rightarrow CH_4(g)+H_2O(g)[/tex], as 4 moles of gaseous reactants is changed to 2 moles of gaseous product, entropy decreases.
In reaction [tex]CH_4(g)+2O_2(g)\rightarrow CO_2(g)+2H_2O(g)[/tex], as 3 moles of gaseous reactants is changed to 3 moles of gaseous product, entropy has no change.
In reaction [tex]N_2O_2(g)\rightarrow 2NO(g)+O_2(g)[/tex] , as 1 mole of gaseous reactant is changed to 3 moles of gaseous product, entropy increases.
helppp nowww plsss!!
Answer:
I believe its C but it could be B
Answer:A
Explanation: i would say the first one
Which of the following statements does not describe the structure of an atom?
A) The electron cloud is a small and compacted space around the nucleus.
B) Inside the nucleus of an atom are protons and neutrons.
C) Protons are positively charged sub-atomic particles.
D) Electrons are negatively charged sub-atomic particles.
If Juan had a glass of milk and dissolved 20g of chocolate milk powder into the milk, by how much will the mass of the milk go up by?
Answer:
20g or 0.2kg
Explanation:
this is because the mass of the powder is 20g and this will be added to the original mass of the milk causing it to increase by that amount
Answer: 20g
Explanation:
You have three BSA working solutions: 5ug/ul, 0.5 ug/ul, and 0.05 ug/ul. Each tube contains 500 ul of solution. How much of which concentration(s) would you pipet into three different centrifuge tubes so you end up with 20 ug, 2 ug, and 0.2 ug of BSA in each tube
Answer:
I would pipet 4 μl of each BSA work solution
Explanation:
To calculate the mass (in μg), we have to multiply the concentration C (in μg/ul) by the volume V (in μl):
C(μg/ul) x V( μl) = mass (μg)
We found the required volume for each solution, as follows:
5 μg/μl x V₁ = 20 μg ⇒ V₁ = 20 μg/(5 μg/μl ) = 4 μl
0.5 μg/μl x V₂ = 2 μg ⇒ V₂ = 2 μg/(0.5 μg/μl) = 4 μl
0.05 μg/μl x V₃ = 0.2 μg ⇒ V₃= 0.2 μg/(0.05 μg/μl) = 4 μl
Therefore, we need to pipet 4 μl of the solutions of concentrations 5μg/μl, 0.5 μg/μl, and 0.05 μg/μl to obtain the masses 20 μg, 2 μg, and 0.2 μg, respectively.
Which one has only 1 type of atom? compound element mixture solution
Answer:
look it updjk jkj vjx cv xckv
Explanation:
look it upvjcvjkcxjbvjkcvbjbcxkjvjdbfcvbdw uvd vjbvjfjv jdbv
Answer:
element :
a substance that is made up of only one type of atom
I hope it helps you ✌
Who has the more valued Exports?
South Africa or Egypt?
pls help ill mark brainliest! star and heart :)
Answer:
Egypt
Explanation:
Hi again
An object has a mass of 72 kg. What is its weight?
Answer:Acceleration due to gravity on the moon is 1/6 times as that on the earth and we know that mass is property of the material it always remains same and weight is measure of gravitational force, hence
mass of object on moon is 60kg and weight =60g/6=10×10=100N
Explanation:
After a recrystallization, a pure substance will ideally appear as a network of __________. If this is not the case, it may be worthwhile to reheat the flask and allow the contents to cool more _________
Answer:
Large crystals
Slowly
Explanation:
Recrystallization is a procedure used to purify an impure compound in a solvent. The concept used here is that the solubility of most of the solids increases with increase in temperature.
Recrystallization is also called as method of fractional crystallization.
After a recrystallization, a pure substance will ideally appear as a network of large crystals. If this is not the case, it may be worthwhile to reheat the flask and allow the contents to cool more slowly.