Four types of observations that indicates occurring of a chemical change are -
Change in ColorExothermic reaction - Large amount of heat is given offPrecipitation reaction - Precipitate is formedRelease of gas - Gas is given off when chemical change occursWhen a chemical change occurs, color of the product is changed. Chemical change is an irreversible change. It cannot be undone as physical change.
A chemical change is an exothermic reaction. A large amount of heat is released when a chemical change occur. As the product formed in a chemical change is changed in its state, color, etc. which requires a large amount of heat.
Precipitate formation occurs in a chemical change as chemical change occurs in aqueous solution where two ionic bonds combine and forms insoluble salt called precipitate.
A chemical reaction releases off a gas. An example is reaction of baking soda and lemon juice. It releases carbon dioxide gas.
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How many molecules are contained in a 4.30-g sample of dimethylmercury?
The number of molecules contained in a 4.30-g sample of dimethylmercury is 1.12 × 10²² molecules.
How to calculate number of molecules?The number of molecules of a substance can be calculated by multiplying the number of moles in the substance by Avogadro's number as follows:
no of molecules = no of moles × 6.02 × 10²³
According to this question, 4.30-g sample of dimethylmercury (C₂H₆Hg) is given. The molar mass of C₂H₆Hg is 230.659 g/mol.
no of moles of dimethyl mercury = 4.3g ÷ 230.659 g/mol = 0.0186 moles
no of molecules of dimethyl mercury = 0.0186 moles × 6.02 × 10²³
no of molecules = 1.12 × 10²² molecules
Therefore, the number of molecules in 4.3g of C₂H₆Hg is calculated to be 1.12 × 10²² molecules.
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What is the empirical formula of a substance that contains 0.250 mol of carbon, 0.500 mol of hydrogen, and 0.250 mol of oxygen?
The empirical formula of the compound is CH₂O.
What is the empirical formula of the compound?The empirical formula of a compound is the simplest formula of a compound showing the elements in the compound combined in their simplest mole ratios.
The empirical formula is determined from the simplest whole number mole ratio in which the elements in the compound combine.
The empirical formula of the compound is calculated below as follows:
mole of carbon = 0.250
mole of hydrogen = 0.50
moles of oxygen = 0.250
Diving by the smallest ratio to convert to whole number ratios
mole ratio of carbon to hydrogen to oxygen will be:
C = 0.25 / 0.25 = 1
H = 0.50 / 0.25 = 2
O = 0.25 / 0.25 = 1
Empirical formula = CH₂O
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A scientist conducted an experiment to determine how the amount of salt in a body of
water affects the number of plants that can live in the water. What is the independent
(testing) variable?
the amount of water
the time it took for the plants to grow
the number of plants
O the amount of salt
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The number of plants in the water is the independent (testing) variable.
What may be altered during an experiment?Anything that may vary or be altered is considered a variable. In other words, it is any factor in an experiment that may be modified, controlled for, or assessed.
Scientists cannot ascribe changes or discrepancies in outcomes to a single source when more than one variable is altered in an experiment. The outcomes may be directly ascribed to the independent variable by looking at and modifying one variable at a time.
What variables are changeable or manipulable?In an experiment, the independent variable is a manipulated variable. It's termed "manipulated" because it can be changed. In other words, you may choose whether to raise or reduce it ahead of time.
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Arrange these acids according to their expected pKą values. (Highest to lowest)
CH₂CH₂COOH
CI2CHCOOH
CICH₂COOH
CICH₂CH₂COOH
You mix a solution with 17.1 grams NaCl, 29.8 grams NaHCO3, and 105 grams of water. What is the mass percent of NaCl in this solution?
Answer:
45.2662%
Explanation:
The sum of the chemicals (sodium chloride) and (Baking powder) and (water) is 151.9, The Salt(sodium chloride) is 29.8 grams and as a percent is 0.298%. 151.9x0.298=45.2662%, happy to help any other time!
Cl₂(g) + F₂(g) 2CIF(g)
Draw Lewis structures for all reactant and product molecules.
Lewis structures for all reactant and product molecules and the show the bonding relationship between atoms of a molecule and the lone pairs of electrons in the molecule
Lewis structure for the reactants and product molecules can be drawn by following the octet rule and considering covalent bonding between the bonded atoms
Here given reaction is
Cl₂(g) + F₂(g) → 2CIF(g)
And lewis structure of reactant means Cl₂(g) + F₂(g) in Cl₂(g) one chlrine has three lone pair attached and another clorine also three lone pair attached whereas F₂(g) also has three pair of lone pair are attached and product means CIF(g) has Cl has three lone pair and F also has three lone pair attached
Lewis structures for all reactant and product molecules are given below
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Based on the image above of Silver from the periodic table, which isotope would be the most abundant?
109
or
107
Based on the image above of Silver from the periodic table, the isotope that would be the most abundant is Ag-107.
What are isotopes?Isotopes are atoms of the same element that differ from each other by their mass.
The difference in the mass of isotopes of elements is due to the difference in the number of neutrons in the nucleus.
The relative atomic mass of an element is the sum of the isotopic mass and relative abundances of the isotopes.
The relative atomic mass of an element is closer to the value of the isotope with the greatest relative abundance.
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a society decides that it needs to produce more corn to feed the growing population what must it do before it begins the production process
The transformation of inputs into outputs is referred to as the production process.
What is meant by the production process?
A production process is a way to use economic resources, such as labor, expensive machinery, or land, to create goods and services for customers.
The transformation of inputs into outputs is referred to as the production process. The primary categories include mass, batch, job, just-in-time, and flexible manufacturing systems.
A production process is a method of delivering goods and services to clients while utilizing resources or economic inputs like labor, expensive machinery, or land.
Therefore, the correct answer is option A. analyze existing resources, such as water availability
The complete question is:
Society decides that it needs to produce more corn to feed the growing population. What must it do before it begins the production process?
A. analyze existing resources, such as water availability
B. determine how people will receive the surplus crops
C. study the profitability of increasing corn production
D. understand who is in a position of authority to produce more
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I need help understanding this is not a test but study material
Explanation:
The law of conservation of mass:
In a chemical reaction, the mass is neither created nor destroyed. In other words, the mass of any one element at the beginning of a reaction will equal the mass of that element at the end of the reaction.
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According to this task, the statement that demonstrates the law of conservation of mass is:
Answer: there are 10 aluminum (Al) atoms represented on each side of the equation.
When 0.384 g of sodium metal is added to an excess of hydrochloric acid, 3990 J of heat are produced. What is the enthalpy of the reaction as written?
The enthalpy of the reaction when 0.384 g of sodium metal is added to an excess of hydrochloric acid and 3990 J of heat is produced is 266 KJ.
The balanced chemical equation of reaction is -
2 Na(s) + 2 HCl(aq) ⟶ 2 NaCl(aq) + H₂(g)
We know that,
weight of sodium metal is 0.384 g
Molar mass of Na is 23 g/mol
we will calculate the number of moles,
Number of moles = Given mass
Molar mass
Moles of Na = 0.348 g = 0.015 mol
23 g/mol
We will calculate the energy in 1 mole of sodium metal
In 0.015 moles of sodium metal, 3990 J of energy is produced.
so, in 1 mole of sodium metal, 3990 J of energy is produced
0.015
In 1 mole, 266000 J of energy is produced.
1 J = 0.001 KJ
266000 J = 266 KJ
The enthalpy of the reaction will be 266 KJ.
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Which of the following is an example of water in a liquid state?
A. ice
B. Steam
C. Snow
D. Rain
A 500 kg car is traveling Northbound towards Rosamond at a rate of 30 m/s. A 2000kg truck is traveling southbound toward LA at 25 m/s. What is the net momentum if North is the positive direction?
The net momentum if North is the positive direction is 20,000Kgm/s.
What is momentum?Momentum can simply be defined as the product of the mass of a particle and its velocity.
Momentum is a vector quantity that possesses a magnitude and a direction.
The Formula of momentum is given below:
Momentum, p = m * v
where;
m is the mass and v is the velocity of the body.
S.I. unit of momentum is kgm/s.
We have the given data as follows:
m1 = 500 kg
v1 = 30 m/s
m2 = 200 kg
v2= 25 m/s
Momentum = m1v1 + m2v2
= (500 * 30) + (200 * 25)
= 15000 + 5000
= 20,000 kgm/s
Momentum = 20,000Kgm/s.
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Which of the following statements is NOT true concerning the decomposition of a simple binarycompound?A) The products are unpredictable.B)The products are the constituent elements.C)Energy is usually required.D)The reactant could be an ionic or a molecular compound.E) The reactant is a single substance
Step 1 -
A decomposition reaction is a reaction in which a compound is decomposed, i.e., we usually heat a substance thus forming new substances, such as gaseous substances.
Generally speaking, a decomposition reaction will involve only one reactant: the substance to be decomposed.
[tex]\text{reactant}\to\text{ product 1 + product 2 + }\ldots[/tex]Step 2 - Examples of decomposition reactions
Let's take a closer look at some examples:
[tex]\begin{gathered} ZnCO_3\to ZnO+CO_2 \\ 2Al_2O_3\to4Al+3O_2 \\ H_2CO_3\to H_2O_{}+CO_2 \\ NH_4NO_3\to N_2O+2H_2O \end{gathered}[/tex]We can already state some conclusions:
a) The products are not always the same. They depend on the reactant. Therefore, they are not always predictable.
b) The reactant can be an ionic compound (such as ZnCO3) but also a covalent compound (such as H2CO3).
c) The reactant does not decompose into its constituent elements.
Step 3 - Finding the wrong answer
Therefore, the only wrong answer is item b), the products are the constituent elements.
Balance the following Equation:
A LI₂CO3 (s) + B HCI (aq) -> C LICI (aq) + D H₂O (1) + E CO₂ (g)
a) A = 1; B = 1; C = 1; D = 1; E = 1
b) A= 1; B = 1; C = 2, D = 1; E = 1
c) A= 1, B2, C = 2; D = 1; E = 1
d) A=2; B = 1;, C = 1; D = 2; E = 1
Answer:
C is the answer
Explanation:
Li2CO3 + HCl - - - - - - -> LiCl + H2O + CO2
Li. Li. H. Li. H. H. C
C Cl. Cl. O. O. O
O. O. O
2 Li ------>1Li so we put 2 in front LiCl on the right side to make 2Li---->2Li.
1H------->2H so we put 2 in front HCl on left side to make
Li2CO3 + 2HCl - - - - - - -> 2LiCl + H2O + CO2
Why does adding elements such as carbon to flexible metals make the material stronger?
Answer: Carbon strengthens iron by distorting its crystal lattice. This distortion is similar in effect to work hardening.
"Nitric acid forms in the atmosphere through the following balanced reaction:
4NO(g) + 3O2(g) + 2H20 and excess oxygen gas, what is the percent yield for hte reaction?
The percent yield of the reaction is calculated as follows:
Percent yield = actual yield/ theoretical yield * 100 %
The percent yield of the reaction is less than 100%.
What is the percent yield of a given reaction?The percent yield of a reaction is the ratio of the actual yield of a reaction and the theoretical yield of the reaction.
Mathematically:
Percent yield = actual yield/ theoretical yield * 100 %The percent yield of any reaction is never 100& percent because no reaction actually goes to completion forming exactly all the product that is expected.
Considering the give reaction of the formation of nitric acid in the atmosphere:
The equation of the reaction is:
4 NO (g) + 3 O₂ (g) + 2 H₂0 (g) ---> 4 HNO₃ + excess oxygen.
The percent yield will require the actual yield and the theoretical yield in order to be calculated.
For example, if the actual yield is 12 g and the theoretical yield is 15 g, percent yield = 12/15 * 100%
Percent yield = 80%
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balance the equation c3h8o3+o2- co2+h2o
Balanced equation of C3H8O3 + O2 = CO2 + H2O is 2C3H8O3 + 7O2 → 6CO2 + 8H2O
How To Balance C3H8O3 + O2 = CO2 + H2O ?
Balance the equation C3H8O3 + O2 = CO2 + H2O using the algebraic method.
Label Each Compound With a VariableaC3H8O3 + bO2 = cCO2 + dH2O
Create a System of EquationsC: 3a + 0b = 1c + 0d
H: 8a + 0b = 0c + 2d
O: 3a + 2b = 2c + 1d
Use substitution, gauss elimination3a - 1c = 0
8a - 2d = 0
3a + 2b - 2c - 1d = 0
Simplify the result to get the lowest, whole integer values.a = 2 (C3H8O3)
b = 7 (O2)
c = 6 (CO2)
d = 8 (H2O)
Substitute Coefficients and Verify Result2C3H8O3 + 7O2 = 6CO2 + 8H2O
Reactants Products
C 6 6
H 16 16
O 20 20
Since there is an equal number of each element in the reactants and products of 2C3H8O3 + 7O2 = 6CO2 + 8H2O, the equation is balanced.
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Of the chemical formulas MgO, Br₂, Ne, and CO₂,
which represents both an element and a molecule?
Explain your answer.
Br2 represents both an element and a molecule.
A molecule is defined as a group of atoms bonded together. An element is defined as a substance that cannot be chemically broken down further into simpler substances. Br2 is only bromine and it is two bromine atoms boned together to form a molecule.
an empty graduated cylinder weighs 26.145 g when the cylinder contains 48.3 of an unknown liquid it weighs 65.055 g. what is the density of the unknown liquid? put answer in correct significant figures
The density of the unknown liquid 1.88kg/m³
The density of a liquid is a measure of how heavy it is for the amount measured and if you weigh equal amounts or volumes of two different liquids, the liquid that weighs more is more dense and if a liquid that is less dense than water is gently added to the surface of the water, it will float on the water
Here given data is cylinder weighs 26.145 g and when the cylinder contains 48.3 of an unknown liquid and it weighs 65.055 g then we have to find density of the unknown liquid = ?
So density = mass/volume
cylinder weighs + liquid weighs = 91.2g
Density = 91.2g/48.3
Density = 1.88kg/m³
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A 9.6 g object is placed in a graduatedcylinder displacing the volume from 10.0 mLto 13.2 mL.The volume of this object is 3.2 mL.What is its density in g/mL?Round your answer to the appropriatenumber of significant figures.[?] g/mL
ANSWER
T
EXPLANATION
Given that;
The mass of the object is 9.6 grams
The volume of the object is 3.2mL
Follow the steps below to find the density of the object
[tex]\text{ Density = }\frac{\text{ mass}}{\text{ volume}}[/tex]Substitute the given data into the formula above
Convert the volume of the object to cm^3
Recall, that 1mL is equivalent to 1cm^3
Hence, 3.2mL is 3.2 cm^3
[tex]\begin{gathered} \text{ Density= }\frac{\text{ 9.6}}{\text{ 3.2}} \\ \text{ Density = 3.00g/cm}^3 \end{gathered}[/tex]Therefore, the density of the object is 3.00 g/mL
Using the equations
-
N₂ (g) + 3 H2 (g) → 2 NH3 (g) AH = -91.8 kJ/mol
C(s) + 2 H₂ (g) → CH4 (g) AH° = -74.9 kJ/mol
H₂ (g) + 2 C(s) + N₂ (g) → 2 HCN (g) AH° = 270.3 kJ/mol
Determine the enthalpy (in kJ/mol) for the reaction
CH4 (g) + NH3 (g) → HCN (g) + 3 H₂ (g).
According to the given data The enthalpy for the reaction, ΔH rxn is 255.95 kJ/mol.
What is enthalpy ?Enthalpy is a characteristic or state function which resembles energy; it has the same dimensions as energy and is thus measured in joules or ergs. The value of enthalpy is entirely determined by the temperature, pressure, and content of the system, not on the history.
Briefing:Calculate the change in enthalpy for the reaction
CH₄(g) + NH₃(g) → HCN(g) +3H₂(g)
From the given reactions
Reaction 1: N₂(g) + 3H₂(g) → 2NH₃(g) Change in enthalpy: -91.8 kJ/mol
Reaction 2: C(s, graphite) + 2H₂(g) → CH₄(g) Change in enthalpy: -74.9 kJ/mol
Reaction 3: H₂(g) +2C(s, graphite) +N₂(g) → 2HCN (g) Change in enthalpy: +270.3 kJ/mol
Reactions 1 and 2 to get reaction 4 and 5 respectively
Reaction 4: 2NH₃(g) → N₂(g) + 3H₂(g) ΔHo : 91.8 kJ/mol
Reaction 5: CH₄(g) → C(s, graphite) + 2H₂(g) ΔHo : 74.9 kJ/mol
Now, multiply reactions 4 and 3 by half (1/2) to get 6 and 7 respectively
Reaction 6: NH₃(g) → ¹/₂N₂(g) + ³/₂H₂(g) ΔHo : 45.9 kJ/mol
Reaction 7: ¹/₂H₂(g) +C(s, graphite) +¹/₂N₂(g) → HCN (g) ΔHo : +135.15 kJ/mol
Now,
Add reactions 5, 6, and 7 together
Reaction 5: CH₄(g) → C(s, graphite) + 2H₂(g) ΔHo : 74.9 kJ/mol
Reaction 6: NH₃(g) → ¹/₂N₂(g) + ³/₂H₂(g) ΔHo : 45.9 kJ/mol
Reaction 7: ¹/₂H₂(g) +C(s, graphite) +¹/₂N₂(g) → HCN(g) ΔHo : +135.15 kJ/mol
----------------------------------------------------------------------------------------------------------
CH₄(g) + NH₃(g) → HCN(g) + 3H₂(g) ΔH rxn = 255.95 kJ/mol
The enthalpy for the reaction, ΔH rxn is 255.95 kJ/mol
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What electrons participate in chemical bonding?
Answer:
valence electrons
Explanation:
they are the electrons that are in the outermost shell
To test the effectiveness of a new nutrient supplement one group of identical mice is given the supplement and the other group is not given any thing .which is the most complete list of the parts of the
experiment presented in this scenario.
The most complete list of the parts of the experiment presented in this scenario include:
Dependent variableExperimental groupControl group.What is Experiment?This refers to the procedures which are performed in other to support or refute a hypothesis. It is also used to ascertain the authenticity of the claim by other people such as scientists etc who review it.
In the scenario given, we were told that the group of identical mice is given the supplement and the other group is not given any thing which means that the control group is the one which wasn't given anything while the ones who were given something is the experimental group.
The dependent variable is the supplement which was given to the mice and is therefore the reason why option B was chosen as the correct choice.
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Sierra Charter School:
Part 3 Directions: Watch the video: How to calculate Oxidation Numbers Intro Video and take notes throughout the video here and from those notes, write a summary.
An oxidation number is a number assigned to an atom that allows chemists to keep track of how many electrons are available for transfer and whether a particular reactant is being oxidized or reduced in a reaction.
Determine if the substance in question is an element. An unbonded free atom always has an oxidation number of 0. An oxidation number is a number assigned to a compound or element to indicate the number of electrons that have been lost or gained. A negative number indicates that an electron was gained and a positive number indicates that an electron was lost.
Determine if the substance in question is an ion. Aeon has an oxidation number corresponding to the charge. This applies to both ions that are not bonded to other elements and ions, which are part of the ionic compound. The oxidation number explains the ability of elements or compounds that provides or obtain electrons during a chemical reaction.
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electronic configuration of Lithium
The electronic configuration of Lithium is 1s²2s¹.
Which encoding is utilized to represent the arrangement of the lithium electrons?The configuration notation allows scientists to clearly describe and record how electrons are positioned around an atom's nucleus. As a result, it is simpler to comprehend and anticipate how atoms will interact to create chemical bonds.
Lithium is the third element with a total of three electrons. We shall describe the lithium electron configuration with the first two electrons in the 1s orbital. Li's third electron is in the 2s orbital since there can only be two electrons in the 1s orbital. Therefore, Li's electron configuration will be 1s22s1.
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How many moles of silver are present in a silver spoon that has a mass of 12.86 g?
You do not need to type your units into the answer box. Please report your answer with three places after the decimal, and do not use scientific notation.
The number of moles of silver present in a silver spoon that has a mass of 12.86g is 0.12 moles.
How to calculate number of moles?The number of moles of a substance can be calculated by dividing the mass of the substance by its molar mass as follows:
The mass of a substance is the quantity of matter which a body contains, irrespective of its bulk or volume.
The mole of a substance is the amount of substance of a system which contains exactly 6.02214076 × 10²³ elementary entities e.g. atoms, molecules.
moles = mass ÷ molar mass
According to this question, silver spoon has a mass of 12.86g. The number of moles can be calculated as follows:
Molar mass of silver (Ag): 107.8682g/mol
moles = 12.86g ÷ 107.8682g/mol
moles = 0.12 moles
Therefore, 0.12 moles of silver are present in the silver spoon.
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what is the weight in remaining oranges
look at the picture
helppppppppppddjeoeps
Answer:
D.) mole, 6.022 x 10²³
Explanation:
Avogadro's Number is a ratio which states that there are 6.022 x 10²³ particles per every one mole.
what is the ionic equation for Ba(ClO4)2(aq)+K2SO4(aq)⟶BaSO4(s)+2KClO4(aq)?