Answer:
Explanation:1 mole is equal to 1 moles CaCO3, or 100.0869 grams.
A student added 5 grams of calcium chloride, a white solid substance, to 15 grams of water at 220 C. Several observations were made and the student inferred that a chemical reaction occurred.
Which observation best supports the student's inference that a chemical reaction occurred?
Answer:
D
Explanation:
A The calcium chloride dissolves in solution
B The mass of the solution totals 20 g
C The temperature of the solution is 35 degrees
D The solution became lighter in color
The correct answer would be that the solution became lighter in color.
An increase in temperature can also be considered a sign of a chemical reaction but in this case, the dissolution of calcium chloride in water is in itself exothermic.
A change in the mass of the final solution could also be considered a sign of a chemical reaction but in this case, the total mass equals the addition of the individual masses of the reactant.
The dissolution of calcium chloride in water is not enough as evidence of a chemical reaction. Dissolution can be a physical change of which, the evaporation of the water would retrieve the solute.
A change in color, however, is one of the evidence to establish that a chemical reaction has occurred.
The correct option is D.
Why do you see different stars in spring’s night sky than in fall’s night sky? Explain.
Answer:
If observed through the year, the constellations shift gradually to the west. This is caused by Earth's orbit around our Sun. In the summer, viewers are looking in a different direction in space at night than they are during the winter.
Explanation:
Answer:
there it the fact that the earthisspinningand so the starsare staying still and we are spinning
____ Ca3(PO4)2(s) + ____ H3PO4(l) → ____ Ca(H2PO4)2(s) When the equation above is balanced and all coefficients are reduced to lowest whole-number terms, what is the coefficient for H3PO4(l)
The equation can be balanced using suitable integers multiplied either side and can be written as follows:
[tex]\rm Ca_{3} (PO_{4})_{2} + 4 H_{3}PO_{4} \rightarrow 3 Ca (H_{2}PO_{4})_{2}[/tex]
Thus the coefficient of H₃PO₄ is 4.
What is balanced reaction?A balanced chemical equation of a reaction represents all the reactants and products in the perfect stoichiometric ratios where, the number of each element have to be equal in both sides.
The given reaction is an example of combination reaction. The equation can be balanced by equating the number of calcium in the product side by multiplying with 3 and then making the phosphate group also balanced by multiplying by 4 with H₃PO₄.
Thus, the balanced chemical equation written above contains 3 calcium on both side and equal number of phosphate group (6) as well as hydrogens on both side where, the coefficient of H₃PO₄ is 4
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What goes in photosynthesis and what comes out of photosynthesis?
Answer:
Carbon dioxide goes in and oxogen comes out
P.S. Sunlight needed for this process to work
Explanation:
Find the percent of water in Zn3(PO4)2 x 7H2O
Answer:
24.66%
Explanation:
To find the percent of water (H2O) in the following compound: Zn3(PO4)2. 7H2O
The atomic mass of the elements are as follows:
Zn = 65g/mol
P = 31g/mol
O = 16g/mol
H = 1g/mol
Hence, molar mass of the compound is as follows:
65(3) + {31 + 16(4)} 2 + 7{1(2) + 16}
195 + 95(2) + 7(18)
195 + 190 + 126
511g/mol
Molar mass of 7H2O
= 7(18)
= 126g/mol
Hence, the percent of H2O in the compound is:
Molar Mass of 7H2O/molar mass of compound × 100
= 126/511 × 100
= 0.2466 × 100
= 24.66%
Which of these statements describes the basic idea of the Valence Shell
Electron Pair Repulsion (VSEPR) theory?
1. Molecules repel one another due to intermolecular forces.
2. There is always an octet of electrons around an atom in a molecule
3. Shared and unshared electron pairs repel each other as much as
possible
4. Electrons are attracted to the nucleus of the central atom.
Answer:
3. Shared and unshared electron pairs repel each other as much as
possible
Explanation:
The variations in the bond angles of molecules and ions can be explained using the valence shell electron pair repulsion theory.
The VESPR model determines the total number of electron pairs (TEP) surrounding the central atom of a specie. The TEP consists of bond pairs BP and lone pairs LP.
All the electron pairs will orient themselves in such a way as to minimize the electrostatic repulsion between them.
The repulsion determines the geometry of the covalent bonds around the central atom. As the number of lone pairs increases from 0 to 2, the bond angles diminishes progressively.
What is the concentration of a stock solution if 20 mL was used to make 400 mL of a 1.44
M solution?
30 M
40 M
50 M
5M
Given :
Volume of stock solution, [tex]V_s = 20\ mL[/tex].
Volume of diluted solution, [tex]V_d = 400 \ mL[/tex].
Molarity of diluted solution, [tex]M_d = 1.44\ M[/tex].
To Find :
The concentration of the stock solution.
Solution :
We know, dilution factor is given by :
[tex]D.F=\dfrac{V_ {diluted}}{V_{stock}}[/tex] ....1)
and [tex]D.F= \dfrac{M_{stock}}{M_{diluted}}[/tex] ....2)
Putting volume in above equation, we get :
D.F = 400/20
D.F = 20
Putting value of D.F in equation 2) we get :
[tex]\dfrac{M_{stock}}{M_{diluted}} = 20\\\\M_{stock} = 20\times 1.44\\\\M_{stock} =28.8\ M[/tex]
The concentration of stock solution is nearest to 30 M.
Therefore, the correct option is 1) 30 M.
PLEASE HELP!!!!
7. According to Mohs Hardness scale, which of these groups of minerals can scratch fluorite? А. B. talc, calcite, and apatite calcite, quartz, and topaz apatite, orthoclase, and corundum diamond, gypsum, and quartz C.
Answer:
B
IS THE CORRECT ANSWER
Plz I need help with this stuff!!!!!!!!!brainly wouldn’t let me post the other pics
How much energy is required to vaporize 14.27 grams of water at its
boiling point? *
Energy required to vaporize : 32.3 kJ
Further explanationThe heat to change the phase can be formulated :
Q = mLf (melting/freezing)
Q = mLv (vaporization/condensation)
Lf=latent heat of fusion
Lv=latent heat of vaporization
Mass of water = 14.27 g
Latent heat of vaporization ( boiling point of 100 ºC) : 2260 J/g
Energy required :
[tex]\tt Q=m.Lv\\\\Q=14.27\times 2260\\\\Q=32250.2~J\approx 32.3~kJ[/tex]
Help plz 15 pointsss
Plz help already late in turning it in
I WILL GIVE BRAINLEST IF YOU ANSWER THIS QUESTION QUICKLY!!!
what is an orbital?
Answer:
Electric Patterns and has many different variations.
Explanation:
can you pls help me with this question
Answer:
probably c
Explanation:
Answer: I feel like the correct answer is choice C but I really don’t know how to explain it..
Can someone define these for me
Answer:
These are all in order....
Explanation:
- closed system usually absorbs thermal energy from its surroundings, which is heat transfer into the system
- a solute is a substance dissolved in another substance, known as a solvent
- A solvent is a substance that dissolves a solute, resulting in a solution. A solvent is usually a liquid but can also be a solid, a gas, or a supercritical fluid
- a liquid mixture in which the minor component (the solute) is uniformly distributed within the major component (the solvent)
- a nuclear reaction in which a heavy nucleus splits spontaneously or on impact with another particle, with the release of energy
- a nuclear reaction in which atomic nuclei of low atomic number fuse to form a heavier nucleus with the release of energy.
- Half-life is the time required for a quantity to reduce to half of its initial value
- the determination of the age or date of organic matter from the relative proportions of the carbon isotopes carbon-12 and carbon-14 that it contains. The ratio between them changes as radioactive carbon-14 decays and is not replaced by exchange with the atmosphere.
- any system closed to all transfers of matter and energy, the mass of the system must remain constant over time, as the system's mass cannot change, so quantity can neither be added nor be removed
What is the advantage of using Microsoft Excel to create a graph, as opposed to pen and paper?
Chemistry class I NEED HELP FAST
Answer:
the advantage of using Microsoft Excel to create a graph, as opposed to pen and paper is it will help you get the right answer
Explanation:
Much of the earth’s heat is retained in the
crust.
wind.
oceans.
mountains.
d) velocity ratio =_________ Iload distance
Answer:
velocity ratio is defined as the ratio of distance moved by effort and load in the same time interval
Explanation:
1. An element is defined by the number of:
Electrons
Protons
Neutrons
Chemical Bonds
lons
Answer:
The correct answer for this question would be B) Protons
Explanation:
I got it right on my test (Can I have brainlyest)
PLS PLS PLS HELP I WILL MARK YOU BRAINLYEST PLS
Answer:
A: Endoplasmic reticulum
B: Chroloplast
C: Mitochondrion
D: Cytoplasm
E: Cell wall
Explanation:
Please help me #6!!!!!!!!
Fill in the blanks. A person would weight more on Neptune than on planet blank
because
blank
A person would weigh more on Neptune than on planet earth because the gravitational field strength is stronger on Neptune.
A person would weight more on Neptune than on planet earth because the gravitational force in neptune is more.
What is gravitational force?Gravitational forces is a kind of attraction force which is present between two objects of masses.
Gravitational force on the neptune planet is more as compared to the gravitational force on the earth. So the mass of any object present in the neptune is more than the earth.
Hence a person would weight more on Neptune than on planet earth because gravitatinal force in neptune is more.
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WILL GIVE BRAINLIEST (major help!!! need now!!!) David observed properties of four different compounds, only one of which is an ionic compound. His observations are shown in the chart.
A 2-column table with 4 rows. The first column labeled compound has entries W, X, Y, Z. The second column labeled observations has entries is a hard solid, melts at 44 degrees C, has a molecular structure; is a brittle solid, does not conduct electricity in water, has a crystal structure; is a hard solid, conducts electricity, has a molecular structure; is a brittle solid, melts at 801 degrees C, has a crystal structure.
Which is most likely the ionic compound?
W
X
Y
Z
Answer:
B. X
Explanation:
Answer:
The answer is D
Explanation:
Wave W is being diffracted, Wave X is being reflected, and waves Y and Z are being refracted.
how does an electron emit light?
Answer:
by moving between defined energy levels
Choose the molecule with the strongest internal bond, (intra-, not intermolecular bond)
Answer:
A
Explanation:
The molecule with the strongest intramolecular bond is HF. Hydrogen fluoride is the answer due to the strong and highly electronegative nature of Fluorine.
Fluorine is the most electronegative element in nature. When it combines with other substances, due to its electronegative property, it draws most of the electrons closest to itself in the bond. This tendency and ability makes the shared electrons closer the fluorine in the bond. The strong polarization that ensues confers a very strong covalent bond pair on the bond formed.The molecule with the strongest internal bond is HF and the correct option is option A.
An intramolecular bond, also known as a chemical bond, refers to the attractive forces that hold atoms together within a molecule. It involves the sharing, transferring, or rearrangement of electrons between atoms to achieve a more stable configuration.
There are three primary types of intramolecular bonds:
Covalent Bond: In a covalent bond, atoms share electrons to achieve a more stable electron configuration. This bond is formed between nonmetal atoms.Ionic Bond: An ionic bond is formed when there is a complete transfer of electrons from one atom to another. It involves the attraction between positively and negatively charged ions. Ionic bonds typically occur between a metal and a nonmetal.Metallic Bond: Metallic bonding occurs in metals and is characterized by a "sea of electrons" in which the valence electrons are delocalized and free to move within the metal lattice. This allows metals to conduct electricity and exhibit other unique properties.Thus, the ideal selection is option A.
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How many moles are in 2.91 x 10^22 molecules of Helium?
Answer:
0.048 molesExplanation:
To find the number of moles in a substance given it's number of entities we use the formula
[tex]n = \frac{N}{L} \\[/tex]
where n is the number of moles
N is the number of entities
L is the Avogadro's constant which is
6.02 × 10²³ entities
From the question we have
[tex]n = \frac{2.91 \times {10}^{22} }{6.02 \times {10}^{23} } \\ = 0.048338...[/tex]
We have the final answer as
0.048 molesHope this helps you
How many grams of CaCI2 (molar mass = 111 g/mol) are needed to prepare 100.mL of 0.100 M CI-(aq) ions?
a.) 0.555 g
b.) 1.11 g
c.) 2.22 g
d.) 5.55 g
I will mark as brainliest if you give the correct answer (brief explanation only, no worries)
Answer:
a
Explanation:
Because that is the answer
Solid carbon dioxide (CO2), also known as dry
ice, changes into a gas at room temperature. An
image of this change can be seen below.
Is this an example of a physical change? Why
or why not?
Answer:
yes
Explanation:
yes because the ice changes forms physically and can be changed back. not 100% sure tho
Answer:
shiii ion even know like i cant even tell u tha
Explanation:
bro 2 of my bruddas got locked up 2 days ago one of em got shot before the cops took him
Agree or disagree
one rotation of the earth occurs everyday or 24 hours
Answer:
Agree
Explanation:
The rotation of earth happens about once every 24 hours.
Which is the formula for iodine tribromide?
IBr
IB3
IBr3
I3Br
Answer:
the answer is c IBr3
Explanation:
The chemical formula for iodine tribromide is IBr₃ as it has 1 iodine and 3 bromine atoms.
What is chemical formula?
Chemical formula is a way of representing the number of atoms present in a compound or molecule.It is written with the help of symbols of elements. It also makes use of brackets and subscripts.
Subscripts are used to denote number of atoms of each element and brackets indicate presence of group of atoms. Chemical formula does not contain words. Chemical formula in the simplest form is called empirical formula.
It is not the same as structural formula and does not have any information regarding structure.It does not provide any information regarding structure of molecule as obtained in structural formula.
There are four types of chemical formula:
1)empirical formula
2) structural formula
3)condensed formula
4)molecular formula
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