PLZ HELP what is a sign that a chemical change has happened ​

Answers

Answer 1

Answer:

Some signs of a chemical change are a change in color and the formation of bubbles. The five conditions of chemical change: color change, formation of a precipitate, formation of a gas, odor change, temperature change.


Related Questions

Which statement describes a condensation reaction?

A. monomers break away when one forms a double bond monomers break away with the addition of a water molecule.
B. Two monomers combine when one adds to the double bond of another.
C. Two monomers form a new bond with the loss of a water molecule .

Answers

The statement that describes a CONDENSATION reaction is that two monomers form a new bond with the loss of a water molecule . That is option C.

CONDENSATION REACTION involves the combination of two or more molecules(monomers) of water. In  reaction, a new bond is usually formed.

The characteristics of a condensation reaction includes:

formation of complex molecules (combination of two smaller monomers),water is usually given off as by product it requires a catalyst for a complete reaction to occur

A reaction is called a condensation reaction because a small molecule such as water is released as a byproduct.

A typical example of a condensation reaction is the condensation of amino acids to form dipeptide. The  −OH  from the carboxyl group of one amino acid combines with a hydrogen atom from the amine group of the other amino acid to produce water.

Therefore, the statement that describes a CONDENSATION reaction is that two monomers form a new bond with the loss of a water molecule. That is option C

Learn more about condensation here:

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Which of the following would not be considered matter?
clouds
trees
rain
air
light

Answers

Answer:

light

Explanation:

Have a nice day

Answer:

light

Explanation:

A gas occupies 210 mL at -73°C to have the same gas occupy 360 mL:
should the temperature be increased or decreased?
what is the new temperature? __ K

Answers

Answer:

a. The temperature should be increased.

b. 342.86K

Explanation:

Using Charles law equation as follows:

V1/T1 = V2/T2

Where;

V1 = initial volume (mL)

V2 = final volume (mL)

T1 = initial temperature (K)

T2 = final temperature (K)

According to this question, the following information were given:

V1 = 210mL

V2 = 360mL

T1 = -73°C (-73 + 273 = 200K)

T2 = ?

Using V1/T1 = V2/T2

210/200 = 360/T2

Cross multiply

200 × 360 = 210 × T2

72000 = 210T2

T2 = 72000/210

T2 (new temperature) = 342.86K

A(n) _____ is a hydrocarbon in which one or more hydrogen atoms is replaced by a -COOH and a -NH2 group. aldehyde carboxylic acid alcohol amino acid

Answers

Answer:

Amino Acid

Explanation:  

It's part of the Amino group, which are substituted hydrocarbons.

When NH₂  and  COOH  replaces hydrogens on the same carbon atom in a molecule, an Amino acid is formed.

What group is a COOH?

COOH : a Carboxylic Acid group!

ASAP
Which of the following describes a characteristic of water that makes it cohesive in nature?

A - It has a partial negative charge on hydrogen and a partial positive charge on oxygen.
B - It has a linear molecular structure with H-O-H arranged in a straight line.
C - It has a vast electronegativity difference between its constituent atoms.
D - It requires a high amount of heat to raise or drop its temperature.

Answers

The answer is C.

The vast difference in electronegativity of the oxygen and hydrogen in water, the O-H bond is polar.

The characteristic of water that makes it cohesive in nature is that It has a vast electronegativity difference between its atoms. So, option C is correct one.

Why water is cohesive in nature?

The water molecule contains two hydrogen atoms and oxygen atom.

The electronegativity of hydrogen atoms and oxyegen atom is 2.1 and 3.44

Due to high electronegativity of oxygen ,it can attract the bonded pair of electron of hydrogen and form a strong bond and make it cohesive in nature.

What are major characteristics of water?

The water molecule have unique characteristics among all some are given below.

Water is polar, with partial positive charge on two hydrogen and partial negative charge on one oxygen.

Water is act as solvent and dissolves the polar and ionic substance.Water has high heat of vaporization.Water has cohesive and adhesive properties.Water has high heat capacity.

learn about water molecule Here,

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from the equation 2PbO + C = 2Pb + CO2, detemine which one is reactant is oxidised and which is reduced.​

Answers

Answer:

Explanation:

C is oxidised because C up to C+4

PbO is reduced because PbO from Pb2+ down to Pb0

Answer:

lead (Pb) is reduced carbon is oxidized

HELP PLEASE 15 POINTS

The rate law for a reaction is found to be rate = k[X]4. By what factor does the rate increase if [X] is doubled?

Answers

X is doubled by 5 and xk is in the fa

Temperature (°C) 5
Heating Curve for Water
160
140
2 120
100
80
60
40
20
0
-20
1 2 3 4 5 6 7
Time (min)
8
9
10
At what temperature does the solid start melting?
0 -20°C
0°C
20°C
80°C

Answers

Answer:

Showing results for Temperature (°C) 5 Heating Curve for Water 160 140 2 120 100 80 60 40 20 0 "-20" 1 2 3 4 5 6 7 Time (min) 8 9 10 At what temperature does the solid start melting?

10. As electrons move through the electron-transport chain,
they lose energy, which is used to form
A. NAD.
B. ADP
C. ATP.
D. GBP

Answers

Answer:

NAD

Explanation:

mark me brainlist please

Answer:

They lose energy which is used to form ATP

What is the oxidation state of S in HSO4^2-? (A.P.E.X)

Answers

I think there is a typo because I've never seen HSO4 2- before in my life. It should be HSO4-. For that, H is 1+ and each Oxygen is 2-0 totaling 8-. So the oxidation state of sulfur +1 - 8 = 7

So the oxidation state of sulfur is +6

PLZ HELP ME WITH MY WORK
For his science fair project, Martin studied the growth of trumpet vines. He grew 20 trumpet vines. All of the conditions were the same, except that he grew 10 in a flower bed without support and 10 in a flower bed near a trellis. The stems of the vines near the trellis twisted around the trellis, and these Yines grew tall and seemed much healthier than the vines grown without a trellis. In fact, four of the vines grown without a trellis died. Which characteristic of living things were the trumpet vines displaying as the stems twisted around the trellis?
A. Movement
B. Response to a stimulus
C. Use of energy
D. Reproduction​

Answers

Answer:

it's B

Explanation:

Climbing plants require an external support to grow vertically and enhance light acquisition. Vines that find a suitable support have greater performance and fitness than those that remain prostrate. Therefore, the location of a suitable support is a key process in the life history of climbing plants

How many moles of Cd and of N are contained in 132.4 g of Cd(N03)2-4H20? (b) How many molecules of water of hydration are in this same amount?

Answers

Answer: The given amount of [tex]Cd(NO_3)_2.4H_2O[/tex] contains 0.430 moles of Cd, 0.860 moles of N and [tex]2.59\times 10^{23}[/tex] molecules of water.

Explanation:

The number of moles is defined as the ratio of the mass of a substance to its molar mass. The equation used is:

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] ......(1)

Given mass of [tex]Cd(NO_3)_2.4H_2O[/tex] = 132.4 g

Molar mass of [tex]Cd(NO_3)_2.4H_2O[/tex] = 308.5 g/mol

Plugging values in equation 1:

[tex]\text{Moles of }Cd(NO_3)_2.4H_2O=\frac{132.4g}{308.5g/mol}=0.430 mol[/tex]

1 mole of [tex]Cd(NO_3)_2.4H_2O[/tex] contains 1 mole of Cd, 2 moles of nitrogen atom (N), 10 moles of oxygen atom (O) and 8 moles of hydrogen atom (H).

So, 0.430 moles of [tex]Cd(NO_3)_2.4H_2O[/tex] will contain = [tex](1\times 0.430) = 0.430mol[/tex] of Cd and [tex](2\times 0.430)=0.86mol[/tex] of N

According to the mole concept:

1 mole of a compound contains [tex]6.022\times 10^{23}[/tex] number of molecules

So, 0.430 moles of [tex]Cd(NO_3)_2.4H_2O[/tex] will contain = [tex]\frac{6.022\times 10^{23}}{1mol}\times 0.430mol=2.59\times 10^{23}[/tex] number of water molecules.

Hence, the given amount of [tex]Cd(NO_3)_2.4H_2O[/tex] contains 0.430 moles of Cd, 0.860 moles of N and [tex]2.59\times 10^{23}[/tex] molecules of water.

ayo could u help me out

Answers

J.J. Thomson's experiments with cathode-ray tubes showed that all atoms contain tiny negatively charged subatomic particles or electrons.

Thomson's plum pudding model of the atom had negatively charged electrons embedded within a positively charged "soup."

Rutherford's gold foil experiment showed that the atom is mostly space with a tiny, dense, positively charged nucleus.

Based on these results, Rutherford proposed the nuclear model of the atom


Answer below:

How many grams of solute is there in 250 mL of a 0.10M CaCl2 solution ?

Answers

Answer:

2.775 g

Explanation:

Given that;

Number of moles = concentration × volume

Concentration = 0.10M

Volume =250 mL

Number of moles = 250/1000 × 0.10

Number of moles = 0.025 moles

Also;

Number of moles = mass/molar mass

Molar mass of CaCl2= 111 g/mol

Mass = Number of moles × molar mass

Mass = 0.025 moles × 111 g/mol

Mass= 2.775 g

list from soft to hard

List the following minerals in order from softest to hardest:
apatite, calcite, talc, quartz, diamond.

Answers

Talc, apatite, calcite, quartz, diamond
I hope this helps. May you mark me brainliest?

The three aspects of the measuring process are units, systems, and instruments.
O True
O False
NEXT QUESTION
ASK FOR HELP
TURNI

Answers

Answer:

the answer for that is false

Answer:

false

Explanation:

the ans is false

hope it helps

In a synthesis experiment you obtain a sample of product on which you do a melting point determination and find a melting point range of 114 to 125 degrees Celsius. The sample is supposed to be acetylsalicyclic acid. What preliminary conclusion(s) can you reach from this one determination

Answers

Answer:

The melting point determination may need improvement- it may not have been done properly, and make sure it was repeated at least once.

Explanation:

Given that we know the actual melting point of pure acetylsalicyclic acid to be 135°, it follows that the process followed to obtain the melting point range of 114 to 125 degrees Celsius must be inaccurate.

Therefore, we can conclude that, the melting point determination may need improvement. It may not have been done properly, and we must make sure it is repeated at least once.

Salt is often used to melt ice on roads during the winter because it lowers the freezing/melting point of water. When salt dissolves in water, individual Na and Cl- ions break away from the salt lattice and become surrounded by water molecules. Why would this cause ice to melt

Answers

Answer:

See explanation

Explanation:

The addition of an impurity lowers the melting point of a solid. If we add salt to ice, the melting point of the ice is lowered.

As this salty water is in contact with the ice, more of the salt dissolves to yield Na^+ and Cl^- and leads to the melting of more ice.

Freezing point is a colligative property hence it is affected by the presence of impurities. Hence, the addition of NaCl causes ice to melt faster.

19. If 23.4 grams of hydrogen gas were produced by the reaction below, how many grams of aluminum chloride were produced? (2 points) 2 Al + 6 HCl yields 2 AlCl3 + 3 H2 516 g AlCl3 774 g AlCl3 1030 g AlCl3 1550 g AlCl3

Answers

Answer:

1040

Explanation:

you can use the mole to mole ratios of aluminum chloride and hydrogen gas,you first have to find the number of moles of hydrogen gas..the number of moles of hydrogen gas are 11.7(23.4/2)

2AlCl3+3H2

2 : 3

x :11.7

3x/3=23.4/3

x=7.8g/mol

then find the number of grams of aluminum chloride

m=n×mr

=7.8×133.341

=1040g

I hope this helps and sorry if it's wrong

Chemistry!! Help me! And explain step by step!

Answers

1st part is ure answer --> 2M

Given mass -> 58 grams

mass of NaCl -> 58.44 approx -> 58 any

moles given-> 1 moles

[tex]Molarity = \frac{moles}{vol \: in \: lts} [/tex]

[tex]Molarity = \frac{1}{0.5} = \frac{10}{5} \\Molarity = 2M[/tex]

What is the mass, in grams, of one mole of any substance known as?
ОА.
atomic mass
OB.
molar mass
O C.
molecular weight
OD.
atomic number

Answers

Answer:

I think it's answer would be A

6. 240J of electric energy flows into a certain light bulb every second, and some energy is transformed into
light energy while some 'waste' thermal energy is also generated. If 200J of thermal energy is generated each
second, what is the efficiency of this bulb? (Hint: Pay good attention to what energy values you've been
given, before you start plugging them into the efficiency formula.)
Looking for
Solution
Given
I
Relationship Formula

Answers

Answer:

don't know

Explanation:

try it your self

try it your self

try it your self

try it your self

try it your self

try it your self

Wich one is it - this is biochemistry

Answers

Answer:

O=O is not a compound; it's a molecule.

Answer:

it is O double bond

Explanation:

because it is not attached with another different molecule like Hydrogen Carbon Sulfur etc. H2O or CO2(these are compounds)

The presence of which gas makes the planets Uranus and Neptune appear blue?
a. helium
b. hydrogen
c. methane
d. nitrogen

Answers

Answer:

C. METHANE

Explanation:

The blue color of both the ice giants can be contributed to the presence of methane in their upper atmospheres. Methane absorbs most of the red light incident on the planets which makes them appear blue in color.

An inorganic salt is composed of 17.6% sodium, 39.7% chromium, and 42.8% oxygen. What is the empirical formula of this salt?

Answers

Empirical formula : Na2 Cr2 O7

How much heat is added if .0948g of water is increased in temperature by .728 degrees C?


.289 J

.803 J

1.46 J

.055 J

Answers

Answer:

0.289J of heat are added

Explanation:

We can relate the change in heat of a substance with its increasing in temperature using the equation:

q = m*ΔT*S

Where Q is change in heat

m is mass of substance (In this case, 0.0948g of water)

ΔT = 0.728°C

S is specific heat (For water, 4.184J/g°C)

Replacing:

q = 0.0948g*0.728°C*4.184J/g°C

q = 0.289J of heat are added

How many moles of oxygen are required to react completely with 5 mol C8H18?

Answers

Answer:

62.5 moles of O₂.

Explanation:

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

2C₈H₁₈ + 25O₂ —> 16CO₂ + 18H₂O

From the balanced equation above,

2 moles of C₈H₁₈ reacted with 25 moles of O₂.

Finally, we shall determine the number of mole of O₂ needed to react with 5 moles of C₈H₁₈. This can be obtained as shown below:

From the balanced equation above,

2 moles of C₈H₁₈ reacted with 25 moles of O₂.

Therefore, 5 moles of C₈H₁₈ will react with = (5 × 25) / 2 = 62.5 moles of O₂.

Thus, 62.5 moles of O₂ is needed for the reaction.

Why does increasing the temperature make a solid dissolve faster?

- The solvent molecules bump into the solid more often.
- The solid is melted before mixing into the liquid.
- The chemical bonds of the solid are broken faster.
- The pressure of the solute on the solid is increased.

Answers

Answer:

The solvent molecules bump into the solid more often

Explanation:

Increasing the temperature makes a solid dissolve faster because the solvent molecules bump into the solid more often.

What happens when you increase the temperature of the solvent?

If we heat the solvent, the average kinetic energies of its molecules increase. Hence, the solvent is able to dislodge more particles from the surface of the solute. Thus, increasing the temperature increases the solubilities of substances. For example, sugar and salt are more soluble in water at higher temperatures.

Does raising the temperature make a substance dissolve faster in a solvent?

The temperature of the solvent is another factor that affects how fast a solute dissolves. Generally, a solute dissolves faster in a warmer solvent than it does in a cooler solvent because particles have more energy of movement.

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The atomic mass of calcium is calculated by adding the mass (amount) of

A) Protons and Electrons
B) Protons and Neutons
C) Electrons and Neutons
D) Protons and Protons​

Answers

Answer:

B. Protons and Neutrons

Answer:

Option"B" is correct.

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0.2g of water represents how many mole?

Answers

Answer:

0.0111moles

Explanation:

as moles = mass/ mr(16+1+1)

so 0.2g / 18

gives you 0.111moles

hope this helps :)

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