A teacher demonstrates a chemical reaction. A student
observes that the test tube in which the reaction occurs
becomes warm. What is the source of the thermal
energy generated by the reaction?

Select one:

A. potential energy absorbed by the reaction

B. breaking bonds of the reactants

C. kinetic energy absorbed by the reaction

D. energy stored in the reactants

Answers

Answer 1

Answer: B, breaking bonds of the reactant.

Explanation:

This reaction is taking in energy and we know this because it says it 'becomes warm'.

Endothermic reactions take in heat/energy from the surroundings and bond breaking occurs during an endothermic reaction.

Answer 2

B. breaking bonds of the reactants which emits heat energy.

The test tube in which the reaction occur is warm because the heat energy is released due to the making of new bonds. When the new bonds are formed, energy is released in the form of heat.

Energy is needed to break bonds so it absorbed the bonds so we can say that bond-breaking is an endothermic process while on the other hand, energy is released when new bonds form so we can say that bond-making is an exothermic process.

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Related Questions

What is the mass of 2.542 × 1026 atoms of F?

Answers

Answer:

7.98 × 10^3grams.

Explanation:

To find the mass of fluorine in the number of atoms provided, we first divide the number of atoms by Avagadros number (6.02 × 10^23atoms) to get the number of moles in the fluorine atom. That is;

number of moles (n) = number of atoms (nA) ÷ 6.02 × 10^23 atoms

n = 2.542 × 10^26 ÷ 6.02 × 10^23

n = 0.42 × 10^ (26-23)

n = 0.42 × 10^3

n = 4.2 × 10^2moles

Using mole = mass ÷ molar mass

Molar/atomic mass of fluorine (F) = 19g/mol

mass = molar mass × mole

Mass (g) = 19 × 4.2 × 10^2

Mass = 79.8 × 10^2

Mass = 7.98 × 10^3grams.

why do non-metal aroms form covalent bonds e.g. H2O​

Answers

Answer:

Covalent bonds usually occur between nonmetals. For example, in water (H2O) each hydrogen (H) and oxygen (O) share a pair of electrons to make a molecule of two hydrogen atoms single bonded to a single oxygen atom. ... Covalent compounds tend to be soft, and have relatively low melting and boiling points.

why are the Alkali Metals the first row of the periodic table?

Answers

Explanation:

All atoms naturally want to have a completely full outermost shell of electrons.Howevee, elements in that first column of the periodic table all have one electron in their outermost shell. ..."since the alkali metals only have one valence electron,they typically achieve this state by giving up that electron.

I hope it's helpful!

Because they typically only have one valence election, and the first row is labeled “1.”

The combustion of a sample of butane, C4H10 (lighter fluid), produced 2.46 grams of water.
2 C4H10 + 13O2 -------> 8CO2 + 10H2O
(a) How many moles of water formed?
(b) How many moles of butane burned?
(c) How many grams of butane burned?
(d) How much oxygen was used up in moles?
(e) How much oxygen was used up in grams?

Answers

a. 0.137

b. 0.0274

c. 1.5892 g

d. 0.1781

e. 5.6992 g

Further explanation

Given

Reaction

2 C4H10 + 13O2 -------> 8CO2 + 10H2O

2.46 g of water

Required

moles and mass

Solution

a. moles of water :

2.46 g : 18 g/mol = 0.137

b. moles of butane :

= 2/10 x mol water

= 2/10 x 0.137

= 0.0274

c. mass of butane :

= 0.0274 x 58 g/mol

= 1.5892 g

d. moles of oxygen :

= 13/2 x mol butane

= 13/2 x 0.0274

= 0.1781

e. mass of oxygen :

= 0.1781 x 32 g/mol

= 5.6992 g

0.137moles of water is formed, 0.0274 moles or 1.5892 g of butane burned and 0.1781 moles or 5.6992 g of O₂ is used.

What is combustion reaction?

Those reaction in which fuel is oxidized by the oxygen molecules and produce carbon dioxide and water molecule.

Given chemical reaction is:
2C₄H₁₀ + 13O₂ → 8CO₂ + 10H₂O

Given mass of water = 2.46 grams

Moles will be calculated as:

n = W/M, where

W = given mass

M = molar mass

(a) Moles of water formed is calculated as:

Moles of water n = 2.46g / 18 g/mol = 0.137moles

(b) From the stoichiometry of the reaction, it is clear that:

10 moles of water = produced by 2 moles of butane

0.137 moles of water = produced by 2/10×0.137=0.0274 moles of butane

(c) Weight of butane is calculated by using moles:

W = 0.0274 × 58 g/mol = 1.5892 g

(d) From the stoichiometry of the reaction, it is clear that:

2 moles of butane = react with 13 moles of O₂

0.027 moles of butane = react with 13/2×0.027=0.1781 moles of O₂

(e) Mass of oxygen is calculated as:
W = 0.1781 x 32 g/mol = 5.6992 g

Hence, (a) 0.137moles, (b) 0.0274 moles, (c) 1.5892 g, (d) 0.1781 moles and (e) 5.6992 g.

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Energy exists in different forms. Which of the following forms of energy best describes the energy stored
in food?
A. electromagnetic energy
B. mechanical energy
C. sound energy
D. chemical energy

Answers

Answer:

D. chemical energy

Explanation:

Food contains chemical energy as chemical energy is stored in bonds.

Calculate the mass (in g) of solute needed to prepare a solution with the given concentration and volume.
Sea water has a concentration of approximately 0.60 M sodium chloride. How much
sodium chloride is dissolved in 1.00 L of solution?
Coke has a concentration of 0.342 M. What mass of sugar (in g) is dissolved in a 2-L
bottle of coke?
What volume of concentrated nitric acid (15.8 M) is needed to prepare 4.0 L of a 2.0 M solution?
What volume of 9.0 M copper (II) sulfate stock solution is needed to prepare 3.0 L of a 5.0 M
solution?

Answers

Answer:

1. 35g NaCl.

2. 234g sugar.

3. 0.506L of concentrated nitric acid are needed.

4. 1.67L of 9.0M copper (II) sulfate are needed

Explanation:

Molarity is defined as the ratio between moles of solute and the volume of the solution.

1. 1.00L * (0.60mol / L) = 0.60 moles NaCl are dissolved

To convert moles to mass we must use its molar mass:

0.60mol NaCl * (58.44g/mol) =

35g NaCl

2. 2L * (0.342mol / L) = 0.684 moles Sugar = moles sucrose

0.684 mol * (342.30g / mol) = 234g sugar

3. 4L of a 2.0M are:

4L * (2.0mol/L) = 8moles

8mol * (1L / 15.8mol) = 0.506L of concentrated nitric acid are needed

4. 3.0L  * (5.0 mol / L) = 15.0 moles copper (II) sulfate.

15.0mol * (1L / 9.0mol) = 1.67L of 9.0M copper (II) sulfate are needed

8.The number of protons plus neutrons is represented by the

a.atomic number
b.mass number
c.atomic mass
d.isotope

Answers

Answer:

c.atomic mass

Explanation:

The total number of protons plus neutrons is called the atomic mass number for the atom.

Round the measurement to 3 significant figures. 13.06

Answers

Answer: 13.1

Explanation: just round the .06 to 1 creating three sig figs.


What element is on period 5 group/family 11

Answers

Answer:

47

Ag

Silver

107.87

Explanation:

An increase in the volume of a substance because of an increase in temperature is called

Answers

Answer:

Its called contraction.

Explanation:

In a fractionating column, what process is caused by heating?

Answers

Answer:

During the fractional distillation of crude oil: heated crude oil enters a tall fractionating column , which is hot at the bottom and gets cooler towards the top. vapours from the oil rise through the column. vapours condense when they become cool enough.

Hope it helps you :)

The fractionating column's crystal clear glass beads provide such a vast surface area for heated vapors to cool and condensed continuously.

The fractionating column is inserted into the mouth of the distillation flask, which contains the saturated solution to be separated.

Heated crude oil is pumped into a tall fractionating column that is heated at the bottom and cools as it rises.

The oil fumes ascend through the column. When vapors cool down sufficiently, they condense. Various heights are used to lead liquids out of the columns.

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Newton's Third Law of Motion states that objects exert equal forces on each other in opposite directions.
Which of the following examples best describe Newton's Third Law of Motion?

Answers

Answer: a truck crashes into a car

Explanation:

The truck drives in a wrong motion which makes the reaction of it crashing.

Which of the following metals (M) will form an ionic compound with nitrogen with the general formula M3N2?

a
lithium (Li)
b
sodium (Na)
c
aluminum (Al)
d
beryllium (Be)

Answers

I thinks it’s D since Be has a charge of 2+ and you are given the formula of M3N2. When you swap and drop the charge of N (3-) and the charge of Be (2+) you get M3N2

Beryllium (Be) will form an ionic compound with nitrogen with the general formula M[tex]_3[/tex]N[tex]_2[/tex]. Therefore, the correct option is option D.

What is metal?

Metal refers to any of a class of substances that have excellent electrical and thermal conductivity, malleability, flexibility, or light reflection. Metals account for over 75% of any and all chemical elements currently known.

Aluminum, iron, salt, potassium, and magnesium are the most abundant elements in the Earth's crust. Most metals can be found in ores, while some, such as copper, gold, platinum, even silver, are frequently found in their free state because they do cannot easily react with other elements. Beryllium (Be) will form an ionic compound with nitrogen with the general formula M[tex]_3[/tex]N[tex]_2[/tex].

Therefore, the correct option is option D.

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Use the half reaction method to balance the following reaction in acid:

I2 + Na2S2O3 -> Na2S2O4 + NaI

Answers

Answer:

I2 + 2S2O3^2- --------> S4O6^2- + 2I^-

Explanation:

The correct equation is;

2Na2S2O3 + I2 → Na2S4O6 + 2NaI

Oxidation half equation;

2S2O3^2- --------> S4O6^2- + 2e-

Reduction half equation;

I2 + 2e ----------> 2I^-

Overall balanced redox reaction equation;

I2 + 2S2O3^2- --------> S4O6^2- + 2I^-

what is C6H6+O2--> CO2+H2O balanced​

Answers

Answer:

2C6H6 + 15O2 → 12CO2 + 6H2O

Answer:

2C6H6 + 15O2 --> 12CO2 + 6H2O

1.a)concentrated sulphuric acid reacts with ethanol to produce ethene
(i) state the conditions for the reaction
.......................................................................
write the equation of the leads to formation of ethene In (a) (i) above.
.....................................................................................
state the property of sulphuric acid shown in reaction (a)(ii)
...................................................................................​

Answers

Answer: a) Temperature of [tex]170^0C[/tex]

b) [tex]C_2H_5OH\stackrel{conc H_2SO_4, 170^0C}\rightarrow C_2H_4+H_2O[/tex]

c) dehydrating agent

Explanation:

Ethanol is heated with an excess of concentrated sulfuric acid at a temperature of 170°C to produce ethene.

The balanced chemical reaction is:

[tex]C_2H_5OH\stackrel{conc H_2SO_4, 170^0C}\rightarrow C_2H_4+H_2O[/tex]

Here concentrated sulfuric acid removes a water molecule from ethanol and thus acts as a dehydrating agent.

How many atoms are in 25.00 g of Li.

Answers

Answer:

6.022×1023 atoms

Explanation:

is chex mix an example of a pure substance or mixture?

Answers

the answer is mixture

An illustration of a mixture is Chex Mix. It is made out of a variety of blended ingredients, including Chex cereal, pretzels, almonds, and spices.

A mixture is a grouping of two or more compounds that are physically mixed but are not chemically bound in chemistry. Each component of the combination keeps its unique characteristics and can be physically separated from it using techniques like filtration or distillation. Both homogeneous and heterogeneous mixtures exist. Homogeneous mixtures, like seawater, have a consistent composition throughout, whereas heterogeneous combinations, like oil and water, have separate phases and an unequal distribution. An illustration of a mixture is Chex Mix.

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Solid to Gas

As a change is state takes place, heat _______ and temperature _______.

A. Increases, stay the same
B. Stay the same, changes
C. Increases, increases

Answers

Answer:

c. c. c c c c c cçcc. ccccccccc

Explanation:

ccc cc

When solid converts to gas then heat is required to break the intermolecular forces of attraction between the particles. In this process heat increase but temperature remains the same. So option A is correct option.

What is phase transition?

Phase transition is a process in which transition takes place from one state to another of a medium on changing temperature or pressure.  Phase transition is a physical process as there is no breaking of old bond and forming of new bonds takes place.

During phase transition temperature remain constant as the extra heat that is given to the system that goes into breaking of  intermolecular forces of attraction between the particles. So overall temperature remains same but heat keeps on increasing. Hence option A is correct.

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How does the number of protons compare to the number of
electrons in a canton

Answers

Answer: The number of protons in cation is more than the number of electrons

Explanation:

cations are positive ions that means that they lose electrons to be stable nd have electron configuration (atomic number ) equivalent to the preceding noble gas

as : sodium 11 , it loses on electron to be stable and its electron configuration is equivalent to neon 10

so ,the number of protons in cation is more than the number of electrons

i hope it helps!

To what category do carnivores, herbivores, and omnivores belong? O A. producer O B. consumer O C. decomposer O D. composer​

Answers

Answer:

B for sure

Explanation:

Because they all consume

Construct an ICE table to calculate the equilibrium concentration of S2− in a solution containing 0.04 mol of Fe(NO3)2. The Ksp of FeS is 8.0 x 10−19. Complete the table by typing in the correct answer, represented by the orange letters in the ICE table. (When typing a number that is between 0 and 1, insert a 0 before the decimal, and type values to two decimal places.)

Answers

Answer: a: 0.04

b: 0

c: x

d: x

e: x

f: 0.04

Explanation:

can someone help me convert these please !

Answers

I have no idea sissssss

NaCl
+
Ba3(PO4)2
Na3PO4
+
BaCl2
1000 grams of sodium chloride is combined with 2000
grams of barium phosphate.
a)What is the limiting reactant?
b) How many grams of excess reactant are left?

Answers

Answer:

a) Sodium Chloride is the limiting reactant.

b)285g of Ba3(PO4)2

Explanation:

a) 1000g Nacl x (1mol of Nacl/58.5g) x (2 Mol Na3PO4/6 mol of NaCl)= 5.70

- 2000g Ba3 (PO4)2 X 1 mol of Ba3 (PO4)2/601.9 x 2 mol of Na3PO4/1 mol of Ba3 (PO4)2= 6.65

Hence; NaCl is the limiting Reactant.

b) 1000g Nacl x (1mol of Nacl/58.5g) x 1 mol of Ba3 (PO4)2/ 6 mol of NaCl x601.9g/1 mol= 1715g  Ba3(PO4)2 USED.

2000g- 1715g=285g of Ba3(PO4)2 Left.

Sodium chloride is a limiting reagent.

284 grams of barium phosphate (excess reactant) are left.

Explanation:

Given:

[tex]6NaCl+Ba_3(PO_4)_2\rightarrow 2Na_3PO_4+3BaCl_2[/tex]

1000 grams of sodium chloride and 2000 grams of barium phosphate.

To find:

The limiting reactant and mass of excess reactant left.

Solution:

Mass of sodium chloride = 1000 g

Moles of sodium chloride =[tex]\frac{1000 g}{58.44 g/mol}=17.11mol[/tex]

Mass of barium phosphate = 2000 g

Moles of barium phosphate =[tex]\frac{2000 g}{601.93 g/mol}=3.323 mol[/tex]

[tex]6NaCl+Ba_3(PO_4)_2\rightarrow 2Na_3PO_4+3BaCl_2[/tex]

According to reaction, 6 moles of sodium chloride reacts with 1 mole of barium phosphate, then 17.11 moles of sodium chloride will react with:

[tex]=\frac{1}{6}\times 17.11mol=2.852 \text{ mol of }Ba_3(PO_4)_2[/tex]

2.852 moles of barium phosphate reacted with 17.11 moles of sodium chloride.

But according to the question, we have 3.323 moles of barium phosphate which is more than 2.852 moles.

This indicates that barium phosphate is an excessive reagent and sodium chloride is a limiting reagent.

Moles of barium phosphate left unreacted:

[tex]=3.323 mol - 2.852 mol = 0.471 mol[/tex]

Mass of 0.471 moles of barium phosphate:

[tex]=0.471 mol\times 601.93 g/mol=283.51\approx 284 g[/tex]

Sodium chloride is a limiting reagent.

284 grams of barium phosphate (excess reactant) are left.

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Which element has the largest atomic radius?

Be
F
Ga
Ba

Answers

Answer:

Ba

Explanation:

The trend for atomic radius is that it increases as you go down and decreases as you go right.

Select the correct answer.

Which phrase describes a polymer?

A.
a branching structure containing 10 carbon atoms and 22 hydrogen atoms
B.
a crystal containing many sodium ions and many fluoride ions
C.
a long chain of carbon atoms with hydrogen atoms attached to them
D.
a molecule containing six carbon atoms arranged in a ring structure
E.
a single atom of calcium bonded to two atoms of chlorine

Answers

C. a long chain of carbon atoms with hydrogen atoms attached to them.

Explanation:

Answer:

C.

a long chain of carbon atoms with hydrogen atoms attached to it

you were stranded on an island with your little brother or little sister and the only thing you have saved in your bag are a plastic envelope with two sheets of bond paper and a roll of sewing thread while waiting for somebody to rescue you how can you use that you materials to cheer up your brother​

Answers

Answer:

well with that you can make a water maker that might make you brother happy because it will keep him alive

Explanation:

Answer:

you could sew a doll for him

or you could punch him in the face and tell him to cheer up

Explanation:

Convert CH4 to C2H6?
Dehydration of alcohol by conc. H2SO4.....?

Answers

Answer:

1.

CH4 + Cl2 → CH3-Cl + HCl

2CH3-Cl +2Na → C2H6

2.

CH3-CH2-OH ---(conc. H2SO4)----> CH2=CH2 + H2O

Explanation:

1. Conversion of methane to ethane

Step 1 - Treat methane with chlorine gas presence of ultraviolet light

CH4 + Cl2 → CH3-Cl + HCl

Step 2 - Treat chloromethane formed in step 1 with the sodium metal and dry ether  (Wrutz synthesis)

2CH3-Cl +2Na → C2H6

2. On treating ethanol with excess of concentrated sulfuric acid, it converts into ethene

CH3-CH2-OH ---(conc. H2SO4)----> CH2=CH2 + H2O

Classify the waves as longitudinal or transverse.

Answers

It’s transverse I think

Answer:

the bell is longitudinal

the secound one is transverse

third is longitudinal

the fourth is transverse

Explanation:

i got it right on my mastery test

Where is the air pressure greater-- at sea level or on a mountaintop? Explain

Answers

Answer:

Air pressure is greater at sea level than at the top of a mountain. The amount of air at sea level is greater than that on top of a mountain.

Explanation:

Please give thanks to all my answers and please mark as brilliant and please follow me

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