Answer:
or example, most samples of the elements hydrogen, oxygen, and nitrogen are composed of molecules that contain two atoms each (called diatomic molecules) and thus have the molecular formulas H2, O2, and N2, respectively. ... A molecule of sulfur is composed of eight sulfur atoms and is therefore written as S8.
"Henry mixed salt and water together in a cup until he observed a clear solution. He measured the mass of the solution. Then he placed the cup outside for several sunny days during the summer. After a week, he observed that only solid salt remained in the cup and the mass had decreased. Henry concluded that a physical and chemical change occurred in this investigation."
Which statements correctly defend or dispute his conclusion?
A.)He is correct. Dissolving salt in water is a physical change, but evaporating the water is a chemical change. Formation of a solid is evidence that a chemical change occurred.
B.)He is correct. Evaporation is a physical change, but dissolving salt in water is a chemical change. The change in mass is evidence that a chemical change occurred.
C.)He is incorrect. Dissolving salt in water and evaporation of the water are both physical changes. The reappearance of salt is evidence that the change was reversible by a physical change, so it could not be a chemical change.
D.)He is incorrect. Dissolving salt in water and evaporation of the water are both chemical changes. The reappearance of salt is evidence that the change was reversible by a chemical change, so it could not be a physical change.
Answer:
C.)He is incorrect. Dissolving salt in water and evaporation of the water are both physical changes. The reappearance of salt is evidence that the change was reversible by a physical change, so it could not be a chemical change.
Explanation:
From the analogy of the problem presented, we can see that Henry is grossly incorrect. His conclusion from the process of the experiment he carried out is completely wrong.
Physical changes are changes that alters the physical properties of matter particularly the form and state.
Chemical changes leads to the formation of a new kind of matter.
We can see that since the salt was obtained back after evaporation, no change has occurred to it.
Therefore, evaporation in itself is a physical change process.
Answer:
c on ed
Explanation:
At the end of which era did the dinosaurs became extinct?
Cenozoic
Jurassic
Mesozoic
Paleozoic
Answer:
Cretaceous Period
Explanation:
Dinosaurs went extinct about 65 million years ago (at the end of the Cretaceous Period), after living on Earth for about 165 million years.
PLEASE ANSWER 80 POINTS
Which response includes all of the following Z1) LiO2 + CO2 → Li2CO3 Z2) Cl2 + 2 NaBr → Br2 + 2 NaCl Z3) HNO3 + KOH → KNO3 + H2O Z4) SO3 + H2O → H2SO4 that are combination reactions, and none that are not combination reactions? 1. Z1 and Z4 only 2. Another reaction or another combination 3. Z1, Z3 and Z4 only 4. Z1 and Z2 only 5. Z1, Z2 and Z4 only
Answer:
z3 xCo2 + 75 = s01 + h20 = Z2
Explanation:
The study of chemicals is called chemistry.
The correct answer is A.
A combination reaction is defined as the joining of two different elements to form a new compound is called a combination reaction. A new compound is always formed in the reaction.
According to the question, in option A the [tex]Li_2Co_3[/tex] is formed and in reaction 4 [tex]H_2So_4[/tex] is formed.
Hence, the correct option is A that is Z1 and Z4.
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Define Strain
HELP ASAPPP!!!!!
Answer:
Ratio of the change in length to original length.
Explanation:
(Δl)/l
10 points!! Please give me work with it and I will mark as brainlist.
Answer the question below. Use the rubric in the materials for help if needed.
A compound is 40.0 % C, 53.3 % 0, and 6.66 % H What is its molecular formula if its molecular mass is 60 g? Show all your work.
Answer: The molecular formula will be [tex]C_2H_4O_2[/tex]
Explanation:
If percentage are given then we are taking total mass is 100 grams.
So, the mass of each element is equal to the percentage given.
Mass of C = 40.0 g
Mass of O = 53.3 g
Mass of H = 6.66 g
Step 1 : convert given masses into moles.
Moles of C =[tex]\frac{\text{ given mass of C}}{\text{ molar mass of C}}= \frac{40.0g}{12g/mole}=3.33moles[/tex]
Moles of O =[tex]\frac{\text{ given mass of O}}{\text{ molar mass of O}}= \frac{53.3g}{16g/mole}=3.33moles[/tex]
Moles of H =[tex]\frac{\text{ given mass of H}}{\text{ molar mass of H}}= \frac{6.66g}{1g/mole}=6.66moles[/tex]
Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.
For C = [tex]\frac{3.33}{3.33}=1[/tex]
For O =[tex]\frac{3.33}{3.33}=1[/tex]
For H = [tex]\frac{6.66}{3.33}=2[/tex]
The ratio of C : O : H = 1: 1: 2
Hence the empirical formula is [tex]COH_2[/tex]
The empirical weight of [tex]COH_2[/tex] = 1(12)+1(16)+2(1)= 30g.
The molecular weight = 60 g/mole
Now we have to calculate the molecular formula.
[tex]n=\frac{\text{Molecular weight }}{\text{Equivalent weight}}=\frac{60}{30}=2[/tex]
The molecular formula will be=[tex]2\times CH_2O=C_2H_4O_2[/tex]
Mixtures can be separated by physical processes.
A sequence of physical processes can be used to separate common salt (sodium chloride)
from a mixture containing sand and common salt only.
Give the order and the correct scientific term for the physical processes used to separate the
common salt from the mixture.
don't know sorry.........
Which of the following is true for an excess reactant?
A) It is the reactant whose atoms remain unbalanced in the equation.
B) It is the reactant that produces a smaller amount of a product.
C) It is the reactant that is left over after the reaction stops.
D) It is the reactant that produces one mole of a product.
Answer:
C) It is the reactant that is left over after the reaction stops.
Explanation:
The excess reactant is the reactant that is left over after the reaction stops. The extent of the reaction is not determined by this reactant.
A limiting reactant is a reactant that is in short supply within a given reaction.
Such reactants determines the extent of chemical reaction.
Limiting reactants are used up in a chemical reaction. The excess reactants remains unchanged after the reaction.Answer: C) It is the reactant that is left over after the reaction stops.
Explanation:
How many atoms are in 4.1 grams of zinc?
Answer:
1 mole of zinc has 6.023 x 1023 atoms
So, 4.1 moles will have 4.1 x 6.023 x 1023 atoms = 24.694 x 1023 atoms
Explanation:
What does the pH of a solution represent?
A. The pH represents the partial pressure of hydrogen gas.
B. The pH tells how quickly a reaction reaches equilibrium.
C. The pH indicates how acidic or basic a solution is.
D. The pH is an indicator of the salt content of a solution.
Answer:
The pH indicates how acidic or basic a solution is.
Explanation:
i just took the test and got it right.
pH of a solution is the measure of how acidic or basic the solution is. It is determined based on the H+ ion concentration in the solution. Hence, option C is correct.
What is pH?pH of a solution is the measure of the H+ ion concentration in a solution. It determines the acidity or basicity of the solution. Mathematically it is the negative logarithm of H+ ions concentration.
pH = - log [H+]
A pH scale can be used to determine the acidity or basicity of a solution. If the basicity is 7, then the solution is neutral. If the pH is less than 7 then the solution is acidic and a pH above 7 is basic solution.
Red- green color in pH scale represent the acidic solution where green is neutral and cyan to dark blue color is given by bases. Using a litmus paper the acidity can be checked based on these color change.
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Why is it not possible to use solid sodium hydroxide directly to make a standard NaOH
solution?
Answer:
Sodium hydroxide is deliquescent (absorbs moisture from the atmosphere) solid. It cannot be weighed accurately. Therefore, it is not possible to prepare a standard solution of sodium hydroxide of accurately known concentration by weighing NaOH.
HELP PLEASE!
Which below, are the smallest basic units of matter?
molecules
ozone
atoms
vitamin E
Answer:
atoms
Explanation:
Which statement describes the conditions in which diamonds form?
A.they form deep underground, in certain areas that are under a great deal of pressure.
B.they form as water evaporates on the shores of very salty bodys of water.
C.They form as water evaporates on the shore of any body of water.
D.they form deep underground, in most regions of earth.
Answer:
a
Explanation:
Two bungee jumpers with the same mass stand on two buildings. One stands on a building 100ft tall and the other a building that is 200ft tall. Which has more potential energy and why?
Bungee jumpers that stand on a 200 ft building
Further explanationGiven
A building 100 ft tall
A building 200ft tall
Required
Which has the greatest potential energy
Solution
Potential energy is owned by an object because of its height
Can be formulated :
PE = m . g . h
g = acceleration due to gravity ,(m/s²)
h = height , (m)
m = mass, (kg)
So PE is influenced by 3 factors:
the object's mass, its gravitational acceleration at that place and its height
Because the mass and gravitational acceleration are the same, the largest PE is owned by bungee jumpers that stand on a 200 ft building
PLZ HELP ME IM FAILING!
Everything you need to know about the question is on the photo
Answer:
C. NH₄Cl
Explanation:
The compound with the element ratio 1 : 4 : 1 from the given choices is NH₄Cl.
An element is a pure substance made up of distinct number of atoms. Elements are unique and are different from other elements because of the nature of their atoms.
We often delineate an element using chemical symbols.
In the compound NH₄Cl;
There are 3 elements:
Number of atoms
N 1
H 4
Cl 1
Is a cell wall found in a plant cell?
Answer:
A plant cell has a cell wall but an animal cell dosnt have one
Explanation:
Brainliest plz
Explanation:
the cell wall surrounds the plasma membrane of the plant and provides tensile strength and protection against mechanical
5.4 g of Aluminium reacts with 300 mL of 0.2 mol/L hydrochloric acid solution. a. Write equation for the reaction taking place. b. Specify which reactant is limiting and which reactant is excess. c. Find volume of the gas collected at S.T.P d. How many grams of salt are produced at the end of the reaction? e. How many grams of the excess reactant are left ate the end of the reaction? Given: Al=27 , H=1 , Cl=35.5
HCl as a limiting reactant
volume of the gas(H₂)= 0.672 L
mass of salt : =2.67 g
mass of excess left : 4.86 g
Further explanationGiven
5.4 g Al
300 mL of 0.2 mol/L HCl
Required
limitng reactants
volume of the gas(H₂)
mass of salt
mass of excess left
Solution
Limiting reacttantReaction
2Al + 6HCl → 2AlCl₃ + 3H₂
mol Al = 5.4 g : 27 g/mol = 0.2
mol HCl = 0.3 L x 0.2 mol/L = 0.06
mol : coefficient of reactants :
Al = 0.2 : 2 = 0.1
HCl = 0.06 : 6 = 0.01
HCl as a limiting reactant(smaller ratio)
Al as an excess reactant
volume of H₂
mol H₂ = 3/6 x mol HCl = 3/6 x 0.06 = 0.03
volume (STP : 1 mol=22.4 L) :
= 0.03 x 22.4 L
= 0.672 L
mass of salt(AlCl₃)
mol AlCl₃ = 2/6 x mol HCl = 2/6 x 0.06 = 0.02
mass AlCl₃ :
= mol x MW
= 0.02 x 133.5
=2.67 g
mass of excess(Al) left
mol (reacted) : 2/6 x mol HCl = 2/6 x 0.06 = 0.02
mol (unreacted) : 0.2 - 0.02 = 0.18
mass = 0.18 x 27 g/mol = 4.86 g
Which of the following is a mechanical wave?
a
An X-ray taking photos of your bones with X-rays
b Ocean waves crashing on the shore
CUV rays giving you a sunburn
d A microwave oven heating food with microwaves
e
Radios picking up radio waves
Answer:
I think A and D and E
Explanation:
that is an example of mechanical wave
Write your explanation on how plants
nake their own food?
imnortont bynroduct of
Answer:
photosynthesis are ligt water and carbon dioxide
Explanation:
Plants make their own food out of inorganic compounds through a process called photosynthesis that takes place in the leaves. The ingredients necessary for photosynthesis are light, water and carbon dioxide.
You eat a snack that has 190 Calories, how many kilojoules did you consume? PLEAS HELP ME I need the work too pls
Answer:
794.96 kilojoules
Explanation:
multiply 190 by 4.184
There are 0.798 kilojoules an individual must consume when he/she takes a snack that has 190 Calories.
What is one Calorie?
One calorie may be defined as a unit for measuring heat wjhich is equivalent to the amount of heat required to increase the temperature of one gram of water one degree Celsius.
According to the question,
The amount of calories a snack contains = 190 calories
Now, you should be required to convert calories into Joules.
1 calorie ≅ 4.2 Joules.
190 calories = 190 × 4.2 = 798 Joules.
Now, according to the conversion factor, 1 kilojoule = 1000 joules
∴ 798 Joules = 798/1000 = 0.798 kilojoules.
Therefore, there are 0.798 kilojoules an individual must consume when he/she takes a snack that has 190 Calories.
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please help with this.
1. Double-Replacement reactions
2. Decomposition
3. Combustion
4. Syntesis
5. Single replacement
Further explanationGiven
Chemical equations
Required
Type of reaction
Solution
1. 2AgNO₃ + MgCl₂ ⇒ 2AgCl + Mg(NO₃)₂
Double-Replacement reactions. Happens if there is an ion exchange between two ion compounds in the reactant
2. 2KBr⇒2K +Br₂
Decomposition
Single compound breaks down in to 2 or more products
3. C₃H₈ + 5O₂ ⇒ 4H₂O + 3CO₂
Combustion
Hydrocarbon and Oxygen reaction and form water and carbon dioxide
4. NaO + H₂O ⇒ NaOH
Syntesis
2 or more reactants combine to form a single product
5. Zn + CuCl₂ ⇒ZnCl₂ + Cu
Single replacement
One element replaces another element from a compound
if an ion has 13 protons and 10 electrons what is the charge on the ion?
Answer:Al3+ indicates an ion of aluminum having a charge of + 3. I.e., since an aluminum atom normally has 13 protons and 13 electrons, this ion has 10 electrons (-10 charge) and 13 protons (+ 13 charge) giving it a charge of + 3 (-10 + 13 = +3).
Explanation:
The ion will have a charge of +3
The components of an atom and their charges are:
protons which have a positive charge electrons which have a negative charge neutrons which have no chargeThe charge of an ion will therefore depend on the number of electrons and protons as they cancel each other out.
The number of excess protons in this ion will be:
= Number of protons - number of electrons
= 13 - 10
= 3
Protons have a positive charge so there will be a charge of +3 as there are 3 excess protons.
In conclusion, this ion will have a charge of +3.
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6.900x10^10 ÷ 4.000x10^8
Answer:
1.725e+18
Explanation:
What is the volume of 4.78g of O2 gas at STP?
Answer:
Explanation:
The trick here is to realize that if you know the volume of a gas at STP, you can use the fact that
1
mole of any ideal gas occupies
22.7 L
under STP conditions to calculate how many moles of gas you have in your sample.
Under STP conditions:
1 mole of an ideal gas = 22.7 L
−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−
In your case, you know that your sample of gas occupies
2.28 L
under STP conditions, which are currently defined as a pressure of
100 kPa
and a temperature of
0
∘
C
.
This means that your sample will contain
2.28
L
⋅
molar volume of a gas at STP
1 mole gas
22.7
L
=
0.10044 moles gas
Now, the molar mass of the gas is the mass of exactly
1
mole of the gas. In your case, you know that you get
3.78 g
for every
0.10044
moles, which means that you have
1
mole
⋅
3.78 g
0.10044
moles
=
37.6 g
Since this is the mass of
1
mole of gas, you can say that the molar mass of the gas is
molar mass = 37.6 g mol
−
1
−−−−−−−−−−−−−−−−−−−−−−−
The best way to separate sesame seeds from salt solution is _____
1 :Filtration
2:Osmosis
3 :Distillation
4 : evaporation
Answer:
Filtration is the answer
Scientists often look at how much isotopes of ______
have decayed to help estimate the age
of a fossil or once-living material.
Answer:
If im correct it’s radioisotope
Explanation:
Scientists often look at how much of isotopes of : Carbon-14 have decayed
To determine the age of fossils archeologist make use of the carbon-14 dating ( i.e. making use of naturally occurring radioisotope ¹⁴C ) which is used to determine the age of fossils or material that were once in living on earth.
Carbon has about three (3) isotopes ( Carbon-12, Carbon-13 and Carbon-14 ) .but Carbon-14 isotope is most useful in determining the age of fossils and once-living things
Hence we can conclude that scientists often look at how much of isotopes of Carbon-14 have decayed to help estimate the age of fossils.
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900 mL of water is added to 100 mL of a 0.1 M solution. What is the new concentration?
0.1M
0.001M
0.0001M
0.01M
Answer:
The new concentration of the solution is;
0.01 M
Explanation:
The question relates to concentration of solution and proportion of mixtures
The given parameters are;
The volume of water added to the 0.1 M solution = 900 mL
The initial volume of the solution to which water was added = 100 mL
Therefore, the total final volume of the solution = 100 mL + 900 mL = 1000 mL = 1 L
The concentration of the solution = 0.1 M
The number of moles present in the solution, 'n', is given as follows;
n = 100 mL/(1000 mL) × 0.1 M = 0.01 moles
Given that no more concentrated solution was added, we have;
The number of moles in the 100 mL solution = The number of moles in the 1,000 mL solution
Therefore, the number of moles in the 1,000 mL (1 L) solution = 0.01 moles
Therefore;
The new concentration of the 1,000 mL (1 L) solution = 0.01 moles/(1,000 mL) = 0.01 moles/(1 L) = 0.01 M (By definition of the molarity of a solution)
The new concentration of the 1,000 mL (1 L) solution = 0.01 M.
D. 0.01 M
Given:
The volume of water added to the 0.1 M solution = 900 mL
The initial volume of the solution to which water was added = 100 mL
So,
The total final volume of the solution = 100 mL + 900 mL = 1000 mL = 1 L
The concentration of the solution = 0.1 M
Firstly we need to find the number of moles which is represented by 'n':
[tex]n = \frac{100mL}{1000mL}* 0.1 M\\\\n = 0.01 \text{moles}[/tex]
The number of moles in the 100 mL solution = The number of moles in the 1,000 mL solution
Thus,
The number of moles in the 1,000 mL (1 L) solution = 0.01 moles
For calculation of new concentration:
Using Molarity formula:
The new concentration of the 1,000 mL (1 L) solution [tex]= \frac{0.01\text{ moles}}{1000mL} = \frac{0.01\text{ moles}}{1L} = 0.01 M[/tex]
The new concentration of the 1,000 mL (1 L) solution = 0.01 M.
Thus, the correct option is D.
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A 2.5 L container holds a sample of hydrogen gas at 291 K and 180 kPa.
If the pressure increases to 350 kPa and the volume remains constant, what will the new temperature be?
Round your answer to one decimal place.
Answer:
The new temperature will be 565.83 K.
Explanation:
Gay Lussac's law establishes the relationship between the temperature and the pressure of a gas when the volume is constant. This law says that the pressure of the gas is directly proportional to its temperature. This means that if the temperature increases, the pressure will increase; or if the temperature decreases, the pressure will decrease.
In other words, Gay-Lussac's law states that when a gas undergoes a constant volume transformation, the ratio of the pressure exerted by the gas temperature remains constant:
[tex]\frac{P}{T} =k[/tex]
When an ideal gas goes from a state 1 to a state 2, it is true:
[tex]\frac{P1}{T1} =\frac{P2}{T2}[/tex]
In this case:
P1= 180 kPaT1= 291 KP2= 350 kPaT2= ?Replacing:
[tex]\frac{180 kPa}{291 K} =\frac{350 kPa}{T2}[/tex]
Solving:
[tex]T2=350 kPa*\frac{291 K}{180 kPa}[/tex]
T2= 565.83 K
The new temperature will be 565.83 K.
help me please asap ...........................................
Oxygen gas is at a temperature of 145 K when it occupies a volume of
1.45 Liters. To what temperature should it be raised to occupy a volume of 6.50
Liters? Show your work. (Express your answer in Kelvin)
Answer:650K
Explanation:
Answer: 650K (1.45/145 = 6.50/x)
Explanation:
80g of calcium reacts with water to form 114g of calcium hydroxide and 2g of
hydrogen.
2 Ca + 2 H0+2CaOH + H,
What mass of water was used in this reaction?
Answer:
31g
Explanation:
80g(Ca)+m(H2O)=114g(CaOH)+2g(H2)
the total mass of the prodicts doesn't change throughout the process
80g+m(H20)=116g
m(H20)=31g