How do you know there was a chemical reaction?

Answers

Answer 1

Answer:

depends

Explanation:

because different chemicals can react they all have different ways of showing a reaction. an example is  given: color, odor, texture  weight solidity

Answer 2

Answer:

U will know there is a chemical reaction, when  light, heat, color change, gas production, odor, or sound. The starting and ending materials of a physical change are the same

Explanation:


Related Questions

Pretend that unbinilium has an atomic mass of 299.01 amu. It is a group 2A element.

In the future, a local scientist reports that they have successfully synthesized 0.0295 moles of unbinilium. How many grams of unbinilium is this?

Do not enter units.

Answers

Answer:

8.82g

Explanation:

In the past mining companies were not made responsible for the clean-up of any of
the mine sites. As a result, abandoned mines had a severe impact on the
environment in Ontario. Which of these is not a result of these mining practices?
a)
Chemical reactions producing sulphuric acid decrease soil and water ph in the
area.
b)
Acid leaching dissolves metals found in the soil thus allowing them to enter
the water system.
c)
Heavy metals which are left tailing ponds can dissolve and enter the water
system.
d)
Old and inefficient mining smokestacks contaminate the soils around
abandoned mine sites.

Answers

D because it was abandoned

When dissolved in water, an acid or a base breaks down into a proton and an electron. two negative ions. a positive and a negative ion. a positive ion and a proton.

Answers

Answer:

got c

Explanation:

When dissolved in water, an acid or a base breaks down into a positive and a negative ion.

What is an acid-base reactions?

An acid–base reaction is a chemical reaction that occurs between an acid and a base. Acid-base reactions can be used to determine pH.

When dissolved in water, acids donate hydrogen ions (H+). Hydrogen ions are hydrogen atoms that have lost an electron and now have just a proton, giving them a positive electrical charge, whereas, bases,  when dissolved in water yield hydroxide ions (OH-).

If a solution has a high concentration of H+ ions, then it is acidic whereas the solution having high concentration of OH- ions, called as  basic.

Thus, from above , it is clear that when dissolved in water, an acid or a base breaks down into a positive and a negative ion.

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(Blank) tells you that the exact momentum and position of a particle can't be known at the same time.

A. The Schrodinger equation
B. Quantum mechanics
C. The uncertainty principle
D. Particle-wave duality

Answers

Answer:

The uncertainty principle

Explanation:

Essentially if you measure the momentum of the particle at a given point, then when you go to measure the position it has moved, thus you don't know the position. Vise versa if you measure the position you only capture a still frame of the particle and no information about it's momentum, which will have changed.

Answer: the uncertainly principle

Explanation:

it basically states you can not know both at the same time

In the equation 2KCIO3 → 2KCI + 302, how many moles of oxygen are produced when 12.61 mol of
KCIO3 decompose completely?
Select one:
O a. 19
Ob. 8.4
O c. 6.3
O d. 13

PLEASE I AM BEGGING PLEASE HELP ME

Answers

Answer:

A 19

Explanation:

2 mole of KClO3 produces 3 mole of O3

2 : 3

1 : 3/2

12.61 : 3/2 × 12.61

12.61 : 18.9

12.61 mole of KClO3 produces 18.9mole of O2.

Scientists hypothesize that a certain species of animal existed in the past.
But, fossils of the species have never been found. Which two statements
could explain why?
A. There were very few members of the species.
B. Their bodies decomposed quickly.
O C. Their bodies contained radioactive atoms.
D. Minerals seeped into their bones.
SUBMIT

Answers

Answer: Fossils of the species have never been found because:-

a. There were few members of the species.

d. Their bodies decompose quickly.

For an organism to become fossil it is important that it do not decompose before it get buried by sediments.

What are fossils?

A fossil is any preserved remains, impression, or trace of any once-living thing from a past geological age.

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Answer: The answer is B and A.

Explanation:

I took the test!

Mass box A = 10 grams; Mass box B = 5 grams; Mass box C-made of one A and one B
How many boxes of B would be required to make 30 grams of C?
hy

Answers

Answer:

2 boxes

Explanation:

==>Given that:

Box A = 10 grams

Box B = 5 grams

Box C= 1 A and 1 B = 15 grams

==>Required:

Number of boxes of B that would make 30 grams of C

==>Solution:

We know that, 1 box of B would give us 15grams of of C when mixed in the right proportion with 1 box of A.

thus,

1 box of B => 15 grams of C

x box of B => 30 grams of C

Therefore x = (30*1)/15

x = 30/15

x = 2

2 boxes of B would be required to make 30 grams of C

The functional group for an ester is: RCHO RCOOH RCOOR ROH

Answers

Answer:

RCOOR

Explanation:

Odyssey ware

RCOOR is the functional group for an ester. An ester is an organic molecule created when an acid and an alcohol interact. The general structure of the compound is RCOOR, where R is an aryl or alkyl group.

What is the way for the structure ?

This functional group is made up of an alkyl or aryl group (R) and a carbonyl group (C=O) linked to an oxygen atom. Two additional carbon atoms, one of which is a member of the carbonyl group and the other of which is a member of the alkyl or aryl group, are joined to the oxygen atom.

The connection between the oxygen atom and the hydrogen atom of the acid is broken during the interaction of an acid with an alcohol to create an ester.of a fresh connection between the oxygen atom and the alcohol's alkyl or aryl group. As a result, the RCOOR functional group is created.

Esters are significant organic substances with many different uses. They serve as solvents and are employed in the synthesis of flavours, perfumes, polymers, medicines, and other products. They are also employed in the creation of fragrances and cosmetics, as well as as lubricants. Other organic compounds can be made using esters as intermediates.

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Determine the [H+] or [OH−] for each of a solutions at 25°C.
Solution B: [H3O+] = 9.99 x 10^-9 M
Solution B: [OH-] = ?

Solution C: [H3O+] = 0.000777 M
Solution C: [OH-] = ?

Answers

Answer:

Solution B: [OH-] = 1×10^–6 M

Solution C: [OH-] = 1×10^–6 M

Explanation:

Solution B:

Hydronium ion concentration, [H3O+] = 9.99×10^–9 M

Hydroxide ion concentration, [OH-] = ?

The Hydroxide ion concentration, [OH-] can be obtained as follow:

[H3O+] × [OH-] = 1×10^–14

9.99×10^–9 × [OH-] = 1×10^–14

Divide both side by 9.99×10^–9

[OH-] = 1×10^–14 / 9.99×10^–9

[OH-] = 1×10^–6 M

Therefore, the Hydroxide ion concentration, [OH-] is 1×10^–6 M

Solution C:

Hydronium ion concentration, [H3O+] = 0.000777 M

Hydroxide ion concentration, [OH-] = ?

The Hydroxide ion concentration, [OH-] can be obtained as follow:

[H3O+] × [OH-] = 1×10^–14

0.000777 × [OH-] = 1×10^–14

Divide both side by 0.000777

[OH-] = 1×10^–14 / 0.000777

[OH-] = 1.29×10^–11 M

Therefore, the Hydroxide ion concentration, [OH-] is 1.29×10^–11 M

In order from left to right, what are the coefficients (front numbers) needed to
balance the following equation? CzH6 + O2- CO2 + H20*​

Answers

Answer:

10CH6 + 10O2 → 10CO2 + 3H20

Explanation:

I really need help!!!
look at the three chemical equations below. How many atoms of each element are in reactants? How many atoms of each element are in the products?
2H2 + O2➔ 2H2O
2Fe203➔ 4Fe+ 3O2
CI2+ 2NaBr➔ 2NaCI+ Br2

Answers

Line one: 4h atoms and 2o atoms on reactant and product side.
Line two: 4fe atoms 6o atoms on reactant and product side.
Line three: 2cl atoms, 2na atoms and 2br atoms on both the reactant and product side.

find the ph of o.o3 h2so4​

Answers

Answer:  1.5

Explanation:

The pH of a solution is given by the formular; pH = - log [ H+ ]. Therefore, for  H2SO4, it is;

pH = - log [ 3 x 10 ∧ -2]

     =  2   - log 3

     =  2 - 0.4771 = 1.5 approximately

Calculate the volume in liters of a 0.00183g / L mercury(1) chloride solution that contains 125 mg of (Hg 2 Cl 2 ) .

Answers

Answer: 68.3L

Explanation:

Density = Mass / Volume

Density =  0.00183 g/L

Mass = 125 mg =  0.125g

Volume =     Mass / Density  =  68.3L

1. A 10.0 g sample of propane, C3H8, was combusted in a constant-volume bomb
calorimeter. The total heat capacity of the bomb calorimeter and water was 8.0
kJ/°C. The molar heat of combustion of propane is -2 222 KJ/mol. If the starting
temperature of the water was 20 °C, what will be the final temperature of the
bomb calorimeter?

Answers

Answer:

The final temperature of the bomb calorimeter is 82.98°C

Explanation:

The given information are;

The mass of the propane sample =  10.0 g

The heat capacity of the bomb calorimeter = 8.0 kJ/°C

The molar heat of combustion of propane is -2,222 kJ/mol.

The starting (initial) temperature of the water, T₁ = 20°C

The final temperature of the bomb calorimeter = T₂

The molar mas of propane = 44.1 g/mol

The number of moles, n, of propane present in 10.0 g of propane is found as follows;

[tex]Number \ of \ moles \ of \ propane, \ n = \dfrac{Mass \ of \ propane}{Molar mass \ of \ propane} = \dfrac{10}{44.1} = 0.227 \ moles[/tex]Which gives;

The heat, Δh, released from the combustion of 10.0 g of propane = 0.227 × -2222 kJ/mol  

Δh = -503.85 kJ/mol  

Heat gained by the calorimeter = Heat released from the combustion of 10.0 g of propane = 503.85 kJ/mol  

Change in heat, Δh[tex]_c[/tex] in the calorimeter = Heat capacity × Temperature change

Δh[tex]_c[/tex] = m × C

503.85 kJ/mol = 8.0 kJ/°C × (T₂ - 20°C)

T₂ = -503.85 kJ/mol/(8.0 kJ/°C) + 20°C = 82.98°C

The final temperature of the bomb calorimeter = 82.98°C

Which of the following elements will not form a polar covalent bond with oxygen?

A. Hydrogen
B. Sodium
C. Oxygen
D. Fluorine

Answers

sodium will form an ionic bond

Answer:

C. Oxygen

Explanation:

Oxygen will not form a polar covalent bond with another oxygen atom because when 2 atoms of the same element bond, it is a nonpolar covalent bond.

Since they are the same element, the 2 oxygens have the same electronegativity and will share their electrons equally.

Polar covalent bonds involve 2 atoms that will share electrons unequally

A ball that has a mechanical energy of 65J has 12J of kinetic energy the ball has ....... of potential energy

Answers

Answer:

53J

Explanation:

Total Energy is the sum of Kinetic energy and potential energy.

2. If the reaction of 5.75 moles of sodium with excess hydrofluoric acid is able to produce 2.49 mol H2, what is the percent yield of hydrogen gas?

Unbalanced equation:
Na + HF –> NaF + H2

94.2%
86.5%
43.3%
23.1%​

Answers

Answer:

86.5%

Explanation:

We'll begin by writing the balanced equation for the reaction. This is given below:

2Na + 2HF –> 2NaF + H2

Next, we shall determine the theoretical yield of the hydrogen gas, H2. This is illustrated:

From the balanced equation above,

2 moles of Na reacted to produce 1 mole of H2.

Therefore, 5.75 moles of Na will react to produce = (5.75 x 1)/2 = 2.88 moles of H2.

Therefore, the theoretical yield of Hydrogen gas, H2 is 2.88 moles.

Finally, we shall determine the percentage yield of Hydrogen gas, H2. This can be obtained as follow:

Actual yield of H2 = 2.49 moes

Theoretical yield of H2 = 2.88 moles

Percentage yield of H2 =.?

Percentage yield = Actual yield /Theoretical yield x 100

Percentage yield = 2.49/2.88 x 100

Percentage yield = 86.5%

Therefore, the percentage yield of Hydrogen gas, H2 is 86.5%.

In this lab procedure, the ___ variable is the number of half-life cycles (time) and the ___ variable is the number (or fraction) of (radioactive) Lincolnium nuclei remaining at that time.

Answers

Answer:

Independent, Dependent

Explanation:

In the given lab procedure, the number of half-life cycles or the time in which the number of nuclei in radio-active substance turns into its half would be characterized as the 'independent' variable as it directly affects the dependent variable i.e. 'the number(or fraction) of Lincolnium nuclei remaining at that time.' The number of nuclei would be the dependent variable as it bears the change or effect of a change in the independent variable(half-life cycle).

Answer:

Its independent and dependent

Explanation:

On Edge 2021

Plants can only
cause mechanical weathering.
Please select the best answer from the choices provided
OT
OF

Answers

Answer:

Ice wedging, pressure release, plant root growth, and abrasion can all cause mechanical weathering. in the cracks and pores of rocks, the force of its expansion is strong enough to split the rocks apart. This process, which is called ice wedging, can break up huge boulders.

Answer:

f

Explanation:

SERE
What type of energy is the sum of an object's potential and kinetic energy?
mechanical energy
electromagnetic energy
chemical energy
thermal enemy

Answers

Answer:

Mechanical energy

Answer:

Mechanical Energy

Explanation:

The mechanical energy is the sum of the objects potential energy (energy the object possess due to its position) and its kinetic energy (energy the object possess due to its motion). Adding this two energies together, gives the total mechanical energy.

How many Liters of 18 M H2SO4 are needed to make 0.5 L of 1.5 M H2SO4

Answers

Answer:

0.04 L

Explanation:

The following data were obtained from the question:

Concentration of stock solution (C1) = 18M

Volume of stock solution needed (V1) =?

Concentration of diluted solution (C2) = 1.5M

Volume of diluted solution (V2) = 0.5L

The volume of the stock solution needed can be obtain by using the dilution formula.

This is illustrated below:

C1V1 = C2V2

18 x V1 = 1.5 x 0.5

Divide both side by 18

V1 = (1.5 x 0.5)/18

V1 = 0.04L

Therefore, the volume of the stock solution needed is 0.04L.

Nitrogen dioxide and water react to produce nitric acid, HNO3,
and nitrogen oxide.
3NO2(g) + H2O(l) — -→ 2HNO3(aq) + NO(g)
a. How many grams of H20 are required to react with 28.0 g
of NO2?
b. How many grams of NO are produced from 15.8 g of H2O?
c. How many grams of HNO3 are produced from 8.25 g of NOZ?

Answers

Answer:

Explanation:

a )

3NO₂(g) + H₂O(l) — -→ 2HNO₃(aq) + NO(g)

3 x 46 g       18 g            2 x 63 g       30 g

138 g of NO₂ requires 18 g of H₂O

28 g of NO₂ requires ( 18 / 138) x 28

= 3.65 g of H₂O.

b )

18 g of H₂O produces 30 g of NO gas

15.8 g of H₂O produces ( 30/18 ) x 15.8

= 26.33 g of NO gas .

c )

138 g of NO₂ produces 126 g of HNO₃

8.25 g  of NO₂ produces (126 / 138 ) x 8.25

= 7.53 g of HNO₃

The pH of a substance can only be determined when it is
a) dried in a powder
b) frozen
c) dissolved in water
d) heated

Answers

The pH of a substance can only be determined when it is
a) dried in a powder
b) frozen
c) dissolved in water
d) heated



It’s frozen
B

The pH of a substance can only be determined when it is frozen. Hence, option B is correct.

What is pH?

pH stands for Hydrogen potentials.

The use of the pH scale is one practical way of quantitatively determining how acidic something is.

If the pH of a solution is less than 7, it is acidic. If the pH is 7, the solution is neutral and if the pH is greater than 7,the solution is basic.

The pH of a substance can only be determined when it is frozen. Hence, option B is correct.

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Find the 5 number summary for the number of chapters in the Old Testament. (Recall that the 5-number summary is the minimum, lower quartile, median, upper quartile, and maximum.)

Answers

Hey, I am doing this project right now too. Did you end up figuring out the answer to this? I do not understand this at all. Message me back pls!

How is alchemy different from modern chemistry?
O A. Alchemy experiments only with living things, and chemistry uses
chemicals
O B. Alchemy was practiced before Aristotle, and chemistry has been
popular since his death.
C. Alchemy is not scientific, but chemistry is based on evidence.
O D. Alchemy covers all areas of science, but chemistry covers only
matter.

Answers

The answer to this is C

Answer:

C. Alchemy is not scientific, but chemistry is based on evidence.

Explanation:

Alchemy was based on mystical beliefs instead of the scientific method.

Chemistry is the study of matter and change based on evidence.

At a certain temperature, Ke = 3 for the reaction NO3(g) NO(g) + O2(g) Find the direction of thereaction if at some point in time in a 1.0 vessel the following respective concentrations were measured; [NO] = 2.0 mol/L, [O2] = 1.0 mol/L and NO3(g) = 0.75 mol/L.

Answers

ScienceDirect is Elsevier's platform of peer-reviewed scholarly literature. It includes thousands of books, journal articles, and other reference materials.

What are thermal plasmas?
plasmas that have particles that collide infrequently
plasmas that reach a temperature equal to their surroundings
plasmas that do not reach thermal equilibrium
plasmas that have only a few particles ionized at any given mom

Answers

Answer: B

Explanation:

Thermal plasmas are plasmas that reach a temperature equal to their surroundings.

Answer:

B

Explanation:

plz help!!!!!!

This equation for the reaction when solid magnesium and solid lead (II) oxide are heated together is:

Mg(s)+Pb(s) => MgO(s)+Pb(s)

a)what does tell you about the position of lead in the reactivity series? explain your answer.
b)rewrite equation as an ionic equation ​

Answers

this shows that magnesium is higher in the reactivity series than lead.

I don't think there can be an ionic equation written because both components are in solid form and neither is in an aqeuos state.

Reactivity series is the progression of the metals based on the activity. In a reaction between magnesium and lead (II) oxide, it can be said that lead is at a lower position in the reactivity series.

What is reactivity series?

Reactivity series is the depiction of the metals in a decreasing order based on their ability to displace the other metal in the reaction. More reactive species are placed at the upper position, while the less reactive species are placed at the lower positions.

In the series, magnesium is placed at the upper part of the series and has high reactivity, whereas lead is placed at the lower level with low reactivity. hence, in the reaction, Mg replaces Pb and forms a bond with oxygen.

The reaction between magnesium and lead (II) oxide cannot be written in the ionic form as all the reactants and the products are in the solid state and not in an aqueous state.

Therefore, lead is at a lower level of reactivity series.

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Given the following thermochemical data C(s) + ½O2(g) ---> CO(g) ∆H1 = -111 kJ/mol C(s) + O2(g) ---> CO2(g) ∆H2 = -395 kJ/mol What is the ∆Hr for the reaction: CO(g) + ½O2(g) ---> CO2(g) ∆Hr = ?

Answers

Answer:

The enthalpy of the reaction asked is -284 kJ/mol.

Explanation:

Given:

[tex]C(s) + \frac{1}{2}O_2(g)\rightarrow CO(g), \Delta H_1 = -111 kJ/mol [/tex]..[1]

[tex]C(s) + O_2(g)\rightarrow CO_2(g) \Delta H_2 = -395 kJ/mol[/tex]...[2]

To find ; [tex]\Delta H_{rxn}[/tex] of following reaction :

[tex]CO(g) + \frac{1}{2}O_2(g)\rightarrow CO_2(g), \Delta H_{rxn} =?[/tex]..[3]

Using Hess's Law:

[2] - [1] = [3]

[tex]\Delta H_{rxn}=\Delta H_2-\Delta H_1=-395 kJ/mol-(-111 kJ/mol)=-284 kJ/mol[/tex]

The enthalpy of the reaction asked is -284 kJ/mol.

Hi :) how to do 4(b)?

Answers

When acid and base solutions react, they produce water and a neutral ionic compound called a salt. The reaction is called a neutralization reaction.

Answer:

they produce water and a neutral ionic compound called a salt. The reaction is called a neutralization reaction.

Explanation:

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