Answer:
A chemical reaction that has a positive ΔH is said to be endothermic , while a chemical reaction that has a negative ΔH is said to be exothermic . What does it mean if the ΔH of a process is positive? It means that the system in which the chemical reaction is occurring is gaining energy.
A solution is prepared by dissolving 15.0 g of table salt in 70.0g of water. Find(a) the mass percent of solute and (b) the mass percent of solvent.
Answer:
[(15g NaCl/(70+15)]*100 = % NaCl
{(70g H2O/(70+15)]*100 = % H2O
Explanation:
A solution is prepared by dissolving 15.0 g of table salt in 70.0g of water. (a) The mass percent of solute is 17.64 % and (b) The mass percent of solvent is 82.35 %.
How to calculate the Mass percent of solute ?Mass percentage = [tex]\frac{\text{Mass of solute}}{\text{Mass of solute + Mass of solvent}}[/tex] × 100
How to calculate the Mass percent of solvent ?Mass percentage = [tex]\frac{\text{Mass of solvent}}{\text{Mass of solute + Mass of solvent}}[/tex] × 100
Here,
Mass of solute (table salt) = 15.0 g
Mass of solvent (water) = 70.0 g
(a) The mass percent of solute
Put the value in above formula we get
Mass percentage = [tex]\frac{\text{Mass of solute}}{\text{Mass of solute + Mass of solvent}}[/tex] × 100
= [tex]\frac{15}{15 + 70}[/tex] × 100
= [tex]\frac{15}{85}[/tex] × 100
= 17.64 %
(b) The mass percent of solvent
Mass percentage = [tex]\frac{\text{Mass of solvent}}{\text{Mass of solute + Mass of solvent}}[/tex] × 100
= [tex]\frac{70}{15 + 70} \times 100[/tex]
= [tex]\frac{70}{85} \times 100[/tex]
= 82.35 %
Thus, we can say that (a) The mass percent of solute is 17.64 % and (b) The mass percent of solvent is 82.35 %.
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why does adding lemon juice to blueberry smoothie make it change colour from purple to pink
In the first half of the citric acid cycle, ____________ is oxidized, yielding a pair of electrons that reduce a molecule of NAD to NADH.
Answer:
isocitrate
Explanation:
The modern-day quantum model of the atom is better than John Dalton’s model because it
A. has set electron orbits.
B. has positive and negative particles in the nucleus.
C. can be represented in one dimension.
D. answers many questions about atoms.
Answer:
its D. answers many questions about atoms.
The modern-day quantum model of the atom is better than John Dalton’s model because it " answers many questions about atoms."
What is quantum model ?This concept also referred to as the quantum mechanical and wave mechanical model, would be the cornerstone of contemporary atomic theory. The fact that an electron inside an atom may only exist in a limited range of states or energy is analogous to a standing wave.
What is John Dalton’s model ?Dalton proposed that the concept of atoms will be used to explain the laws of conservation of mass as well as definite proportions. Imagining atoms as "solid, massy, hard, impenetrable, moving objects," he claimed that almost all matter would be composed of these tiny, indivisible particles.
Dalton also stated that almost no atom might be formed, converted into another, as well as destroyed. The complex shapes of orbitals also known as electron clouds used in the quantum mechanical atomic model are areas of space where an electron is likely to be present. So rather than being based on certainty, this model would be probability based.
Therefore, the correct answer will be option (D)
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The DEA has designated five chemicals often found in spice as _____ controlled substances, making it illegal to sell, buy, or possess these chemicals.
Answer:
I'm pretty sure this doesn't really connect with chemistry much but the answer should be Schedule 1 as stated by the Drug enforcement agency.
Identify the correct chemical name.
Select one:
a. calcium (II) hydroxide
b. chromium hydroxide
c. ammonium calcide
d. ammonium chloride
An aqueous solution has a volume of 2.0 L and contains 36.0g of glucose. If the Molar Mass of glucose is 180g/mol, what is the molarity of the solution
Convert grams of Glucose to moles of Glucose and then solve for Molarity
show all work.
Answer:
moles = 36/180 = 0.2 moles
molarity = 0.2/2 = 0.1 mol/dm3
Nylon is a synthetic material that has many uses. It is used in the production of machine parts, cookware, and fabric. Nylon is made from petroleum and natural gas. Suppose that there were a shortage of petroleum and natural gas. What would companies that produce nylon likely need to do? A. identify a different natural resource that nylon could be made from B. search for nylon in many different parts of the earth C. convert existing nylon back into petroleum and natural gas D. find a way to make nylon without using natural resources
In case of a shortage in petroleum and natural gas, a company should find a way to make nylon without using natural resources.
Nylon is a very important material used in numerous applications. As a result of this, the demand for nylon as a raw material has genuinely been on the high side ever since.
However, nylon production depends on petroleum and natural gas. It is possible that there could be a shortage of these resources since they are obtained from the environment. In such cases, a company should find a way to make nylon without using natural resources.
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Answer:
identify a different natural resource that nylon could be made from
Explanation:
I just did this question
i need help with this asap..
1. What has shininess
2.ability to change its shape
I think it's metal if its abt science
Answer:
i think metal or glass not sure but i think its metal
Explanation:
Jeremy left his bike outside overnight. When he woke up in the morning, there were water drops on the seat. When he went to ride his bike after lunch, he saw the water drops had disappeared. Which statement best describes what happened to the water?
A. The energy from the sun caused the water drops to condense.
B. The energy from the sun caused the water on the seat to boil.
C.The energy from the sun cooled the water, causing it to evaporate.
D.The energy from the sun heated the water, causing it to evaporate.
Answer:
D
Explanation:
a,b, and c wouldn't cause the reaction that Jermey expirenced
Don’t understand this science Question.
Answer:
I got you..you need help but with which question?
Explanation:
Have a great day!
How quickly the electron are moving through the circuit
A.Resistance
B.voltage
C.current
2.The strength with which electrons are pushed through the circuit?
A.Resistance
B.voltage
Current
Answer:
B
Explanation:
because the electrons are moving fast
What does the law of conservation of matter state?
a Matter can be created, destroyed, and changed.
b Matter can be destroyed and created, but not changed.
c Matter can be changed, but not created or destroyed.
d Matter can be created and changed, but not destroyed.
The answer is c. Matter can be changed, but not created or destroyed.
What is the difference between a conductor and an insulator?
explain the electrolysis of MgCl2 in aqueous solution
During electrolysis, a current is passed through the molten MgCl2, and when this happens, the Mg2+ ions move to the negative electrode where they PICK UP OR GAIN ELECTRONS. This is reduction. The Cl- ions move to the positive electrode where they LOSE ELECTRONS. This is oxidation.
What makes solids, liquids, and gases different. Explain the hypothesis, prediction and experiments that can lead to scientific theory.
Answer: Gases, Liquids, and Solids
Gases
Explanation:
Behavior
gas liquid solid
assumes the shape and volume of its container
particles can move past one another assumes the shape of the part of the container which it occupies
particles can move/slide past one another retains a fixed volume and shape
rigid - particles locked into place
compressible
lots of free space between particles not easily compressible
little free space between particles not easily compressible
little free space between particles
flows easily
particles can move past one another flows easily
particles can move/slide past one another does not flow easily
rigid - particles cannot move/slide past one another
a hypothesis is a prediction based on a theory. If the Hypothesis comes true the theory is more accepted.
A scientific theory differs from a scientific fact or scientific law in that a theory explains "why" or "how": a fact is a simple, basic observation, whereas a law is a statement (often a mathematical equation) about a relationship between facts.
Food waste, like a feather or a bone, fall into food, causing
contamination.
Physical
Chemical
Pest
Cross-conta
Answer:
what do I need to do?..
..
Feather or bone when fall into food causing Physical contamination.
Food waste, like a feather or a bone etc fall into food causing Physical contamination because the contaminants such as feather and bone are mixed in the food physically not chemically. These contaminants can be removed through physical means such as with the help of hand.
Some contaminants mix with the food chemically means they react with the food and produce something new. Such type of contaminants are present in liquid form so we can conclude that feather or a bone etc when fall into food causing Physical contamination.
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What type of chemical reaction is Al + FeO --> Al2O3 + Fe
Answer:
single reaction equation
Explanation:
Type of Chemical Reaction: For this reaction we have a single replacement reaction. Balancing Strategies: In this single replacement (also called displacement) reaction the Al and Fe are switching places.
Pls fast pls due today pls pls I don’t wanna fail
Answer:
2:true
3: true
4:false
5: true
Explanation:
Pls help I will give u points pls
Answer:
i think D
Explanation:
The overall shape of a plant cell is most directly related to which of its parts?
Answer: Cell wall
Explanation: Cell wall is a unique structure found only in some specific organisms like plants, bacteria, fungi etc. The cell wall in plants is predominantly made up of a polysaccharide called CELLULOSE. This carbohydrate confers upon the cell "rigidity".
The cell wall is an additive material including the cell membrane that coats the external part of the cell of plants, hence, it gives plant cells their characteristic shape. The cell wall contributes to the overall flexible but rigid shape of the plant cell, protecting the cell against physical or chemical stresses.
Does this aid in joining the two molecules?
Answer:
yes it does aid in joining the two molecules
Explanation:
an atom of chlorine has an amount number of 17 and a mass number of 37. how many protons neutrons, and electrons are in the atom?
Answer: There are 20 protons neutrons in the atom
2KClO3 —> 2KCl2+ 3O2
true if balanced or false if not
reaction type 1: synthesis, 2: decomposition, 3: single replacement, 4: double replacement, 5: combustion
Answer:
False. The balanced equation should be
2KClO3-->2KCl + 3O2
it is a decomposition reaction.
An elephant takes a deep breath, releasing 9.50g of CO2. How many molecules CO2 is this?
Answer:
3 significant figures.
Explanation:
So, a mole is essentially a group of things. In this case, a mole of carbon dioxide will contain
6.022 ⋅ 10 [ by the 23rd power]
molecules of carbon dioxide. In other words, in order to have
1 molecule of carbon dioxide, you need to have 6.022 ⋅ 10 [by the 23rd power] molecules of carbon dioxide.
You know that 5.00 ⋅ 10 [ by the 2nd power] molecules of carbon dioxide are exhaled from the lungs when we breathe out. You can use Avogadro's constant as a conversion factor to help you figure out how many molecules are present.
PLEASSE HELP gotta get the answers neowww, basically just match the letters with the things.
Answer:
North pole-A
South pole- F
Equator- E
Polar Easterlies-C
Prevailing Westerlies-D or B-not sure
Trade Winds-D or B-not sure
Help me:) please and thanks! Part 3
Answer:
then this picture 11 Venkat and one person is
Explanation:
join date 20th December is not a problem with the topic of your name and address of the topic of your name and address of the topic of your name and address of the topic of your life in general is not available in the equation is the topic of your name and address
so nothing in this picture .
Cu(OH)₂ +H₃PO₄ = Cu₃(PO₄)₂+H₂O
how do i balance this equation
balanced equation =
3Cu(OH)2 + 2H3PO4 → Cu3(PO4)2 + 6H2O
SEP Construct Explainations: Explain how a substance's flammability can indicate a chemical change.
Answer:Wood for barbucue.
Explanation:
Ethanol (C2H5OH) reacts with oxygen gas in a combustion reaction. How many liters of carbon dioxide gas are produced at STP when 375 mL of a 75.0% ethanol solution by mass with a density of 1.22 g/mL reacts with excess oxygen?
The volume of carbon dioxide produced when 375 mL of a 75.0% ethanol solution by mass with a density of 1.22 g/mL reacts with excess oxygen is 667.52 L.
We are told in the question that the solution contains 75.0% ethanol solution by mass.
Hence;
Density of solution = mass/volume
mass = Density × volume = 1.22 g/mL × 375 mL = 457.5 g
Mass% = mass of solute/ mass of solution × 100
Mass of solute = x
Mass of solution = 457.5 g
Mass percent = 75.0%
Substituting values;
75 = x/457.5 + x × 100
75/100 = x/457.5 + x
0.75(457.5 + x) = x
343.125 + 0.75x = x
343.125 = x - 0.75x
x = 343.125/0.25
x = 1372.5 g
The equation of the reaction is;
C2H6O(l) + 3O2(g) → 2CO2(g) + 3H2O(l)
Number of moles of ethanol = 1372.5 g/46 g/mol = 29.8 moles
From the reaction equation;
2 moles of ethanol produces 2 moles of carbon dioxide
29.8 moles of ethanol also produces 29.8 moles of carbon dioxide
If 1 mole of carbon dioxide occupies 22.4 L
29.8 moles of carbon dioxide occupies 29.8 moles × 22.4 L/ 1 mole
= 667.52 L
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