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?

Answers

Answer 1

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.


Related Questions

Please help with this I do not under stand

Answers

Answer:

See below:

Explanation:

The grasshopper doesn't require an exchange of gasses (air) using a circulatory system because the gasses directly reach its cell's from the "air sacs" which spread out into tiny tubes close to each cell.

true or false: Fungi are able to carry out photosynthesis, similar to plants

Answers

Answer:

false

Explanation:

Answer:

FALSE ...

Explanation:

However, unlike plants, fungi do not contain the green pigment chlorophyll and therefore are incapable of photosynthesis. That is, they cannot generate their own food — carbohydrates — by using energy from light. This makes them more like animals in terms of their food habits

which one of these elements is the lightest: 1- oxygen , 2- carbon , 3- nitrogen , 4- neon.

idk what neon is but that’s an answer so...

Answers

It would be carbon because its relative atomic mass is 12

What is the formula of iron(iii) oxide?

Answers

Answer:

Fe2O3

Explanation:

Answer:

Fe2O3

This is the chemical formula for iron(iii) oxide.

The total partial obscuring of the Sun or Moon by the Moon or the Earth's
shadow is an

Answers

Answer:

Eclipse

Explanation:

The Awnser is eclipse I think

7)
Mg(s) + 2 HCl(aq) + MgCl2(aq) + H2(g)
What type of reaction is shown above?
A)
decomposition
B)
double replacement
C)
synthesis
D)
single replacement

Answers

Answer:

D)  single replacement

Explanation:

Given reaction:

         Mg       +           2HCl      →      MgCl₂        +        H₂

The reaction shown above is a single displacement reaction.

In a single displacement reaction, a more reactive atom displaces another from a given compound.

The comparison here is between Mg and H.

On the activity series, Mg is higher and more reactive, it will displace H from the solution of HCl. This

This reaction type is called a single replacement reaction.

This particle has mass but no charge.

Answers

Answer:

Neutrons

Explanation:

let me know if it is right or not:)

neutron : a subatomic particle found in the nucleus of an atom. It has no charge (is neutral), and has a mass of 1 amu.

SA
Element Proton number Nucleon number


Х
13
27
Y
8
16
Table 2
Jacheal 2
Element X reacts with element Y to form
compound
What is the molar mass of the compound?


A 43 g mol
C 102 g mol
B 50 g mol
D 113 g mol
SA
31

Answers

Answer:

маликулярная масса ровна  23

true or false, when a material loses thermal energy, it usually contracts.

Answers

Answer:

True

Explanation:

Whenever something loses thermal energy, it contracts and becomes smaller.

Answer: it might be true

Explanation:

Identify the type of reaction: 2AgCl + BaBr2 -> 2AgBr + BaCl2
A) decomposition
B) combustion
C) double replacement
D) single replacement ​

Answers

Answer:

C

Explanation:

Just look at the reactants.

2AgCl + BaBr2

The first reactant is made of 2 elements.

The second reactant is made of 2 elements.

It can't be a decomposition. At this level there is only one reactant made of 2 elements. Something like

2MgO ===> 2Mg + O2

is a decomposition.  One compound breaking down into 2 elements Mg and O.

It can't be a combustion. One of the reactants in a combustion is oxygen. Those equations look like

C3H8 + 5O2 ==> 3CO2 + 4H2O

That would be what a combustion looks like

It can't be a single replacement. They look like

Mg + CuO ===> Cu + MgO

There are elements on both sides of the reaction.

that leaves a double replacement which I wrote about how you distinguish it.

Answer:

c

Explanation:

Based on the context of paragraph 4, what are salient factors?
important factors
ignorable factors
interesting factors
intended factors

Answers

Answer:

importent factors

Explanation:

The salient facts about something or qualities of something are the most important things about them: She began to summarize the salient features/points of the proposal. The article presented the salient facts of the dispute clearly and concisely. SMART Vocabulary: related words and phrases. Very important or urgent.

Answer

The answer is a/important factors. Pls subscribe to Amiredagoat Yt in return.

Explanation:

What is the location of elements in the periodic table related to?

Answers

Answer:

.

Explanation:

An element's location in the periodic table is largely depending on its electrons. The number of valence shell electrons determines its group, and the type of orbital in which the valence electrons lie in determines the element's block. Sometimes during these groups there are more like the alkali metals the non metals and gases :)

500 mL solution of calcium chloride with a concentration of 0.75 mol/L. The mass of solute needed to make this solution is ___ ___ ___ ___ g.

Answers

Answer:

41.63g

Explanation:

Given parameters:

Volume of CaCl₂  = 500mL  = 0.5L

Concentration  = 0.75mol/L

Unknown:

Mass of the solute needed = ?

Solution:

The mass of the solute can be derived using the expression below;

     Mass  = number of moles x molar mass

But,

   Number of moles  = Concentration x Volume

So;

     Mass  = Concentration x Volume x molar mas

Molar mass of CaCl₂  = 40 + 2(35.5) = 111g/mol

     Mass  = 0.75 x 0.5 x 111 = 41.63g

Can someone please help me, I’m taking a test

Answers

Answer:

Im pretty sure its none of these

which of these substances will conduct electricity? CuSO4(s) CuSO4(aq) C5H12(l) CO2(g)

Answers

Answer:

CuSO4(aq)

Explanation:

The aqueous for of CuSO₄ is an electrolyte and it will conduct electricity.

CuSO₄ is an ionic substance and in solid state, it will not have the ability to conduct electricity.

In aqueous form, it will contain free mobile ions which serves as carriers of electric current. In the solid state, the ions are arranged into a crystal lattice and will not conduct a current of electricity. The remaining given compounds will not conduct electricity as they are non-polar and do not have free mobile electrons.

Order the elements from smallest to largest atomic number

Answers

the largest is francium, Z=87 , or caesium, Z=55 ; and the smallest is definitely helium, Z=2 .

Explanation:

make me Brainliest

A beaker containing 6.32 moles of PBr3, contains___
molecules of PBrz.

A) 1712.7
B) 3.1 x 10^24
C) 3.8 x 10^24
D) 271

Answers

Answer:

3.8 x 10²⁴molecules

Explanation:

Given parameters:

Number of moles  = 6.32moles

Unknown:

Number of molecules  = ?

Solution:

The number of moles can be used to derive the number of molecules found within a substance.

Now,

       1 mole of substance contains 6.02 x 10²³ molecules

     6.32 mole of PBr₃ will contain 6.32 x 6.02 x 10²³ = 3.8 x 10²⁴molecules

Using the model of the periodic table, which element pictured represents an unreactive gas?

Answers

Answer:

2

Explanation:

Nobel gasses are not reactive and are the far right group on the periodic table.  This is because they have a full valence electron shell which is the most stable electron configuration.  Most reactions occur in order for an atom to fill its valence shell and since they already have a full valence shell there is no reason for them to react.

Answer fast please What system are your lungs part of
A. Circulatory
B, Respiratory
C. Digestive
D. Skeletal

Answers

Answer:

B. Respiratory System

Answer:

B, Respiratory

Explanation:

When halogens react with metals,they form salts called....

Answers

When halogens react with metals,they form salts called metal halides according to their electronic configuration according to which reaction takes place.

What is electronic configuration?

Electronic configuration is defined as the distribution of electrons which are present in an atom or molecule in atomic or molecular orbitals.It describes how each electron moves independently in an orbital.

Knowledge of electronic configuration is necessary for understanding the structure of periodic table.It helps in understanding the chemical properties of elements.

Elements undergo chemical reactions in order to achieve stability. Main group elements obey the octet rule in their electronic configuration while the transition elements follow the 18 electron rule. Noble elements have valence shell complete in ground state and hence are said to be stable.

Learn more about electronic configuration,here:

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Please answer correctly !!!!!!!!!!!!! Will mark brainliest !!!!!!!!!!!!!!!!!!!!

Answers

Answer:

AG

Explanation:

HOPE THIS HELPS

Write word equation for the chemical reaction that occurs when solid sodium oxide is added to water at room temperature and forms sodium hydroxide (dissolved in the water).

Answers

Answer:

[tex]$Na_2O + H_2O \rightarrow 2NaOH$[/tex]

Explanation:

When solid sodium oxide reacts with water in a room temperature, it forms sodium hydroxide.

The one word equation of the reaction will show or represent the reactants on the left hand side of the arrow and the products on the reaction on the right hand side of the reactants.

Thus the equation of the reaction is :

[tex]$Na_2O(s) + H_2O(l) \rightarrow 2NaOH(aq)$[/tex]

Sodium oxide + water ----[tex]$\rightarrow$[/tex] sodium hydroxide.

The equation for the chemical reaction should be [tex]Na_2O + H_2O \rightarrow 2NaOh[/tex]

Chemical reaction equation:

At the time when the solid sodium oxide reacted with the water in room temperature so it created the sodium hydroxide.

Here the one-word equation represents that the reactant should be on the left-hand side while on the other hand, the product should be on the right-hand side.

Also, it should be like

Sodium oxide + water ---- sodium hydroxide.

Learn more about reaction here: https://brainly.com/question/23552723

Please help❤️

Explain what is meant by noble gas envy.

Answers

Answer:

a phrase that describes how elements what do be stable and non reactive like the noble gas elements are.

According to Newton’s third law of motion, when a hammer strikes and exerts force on a nail, the nail
(a) creates a friction with the hammer.
(b) disappears into the wood.
(c) exerts an equal force back on the hammer.
(d) moves at a constant speed.

Answers

Answer:

C

Explanation:

When a hammer strikes and exerts force on a nail, the nail exerts an equal force back on the hammer. Option C. This is further explained below.

What is Newton’s third law of motion?

Generally, According to Newton's third law, when two bodies contact, they apply forces to each other that are equal in magnitude and opposing in direction.

In conclusion, Newton’s third law of motion certifies that the nail exerts an equal force back on the hammer.

Read more about Force

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PLS PLS PLS HELP PLS I REALLY NEED IT AND I WILL MARK YOU BRAINLYEST:((
PLSSSS

Answers

Answer:

D and A

Explanation:

D is a Mitochondria (the powerhouse of the cell)

A is a Choroplast (the part that takes in the sun)

Question 1
You are making lemonade and the calls for 6 cups Lemon juice (L), 3 Cups of sugar (S) and 5 cups of water (W) to make 12 Cups of Lemonade (LA): your formula is:



6 L + 3 S + 5 W = 12 LA



You are given 9 cups of lemon juice (L), 8 cups of sugar (S) and unlimited water (W).
How many cups of lemonade can you make?

Question 1 options:

9 Cups of Lemonade


12 Cups of Lemonade


18 Cups of Lemonade


32 Cups of Lemonade

Question 2
You are making lemonade and the calls for 6 cups Lemon juice (L), 3 Cups of sugar (S) and 5 cups of water (W) to make 12 Cups of Lemonade (LA): your formula is:



6 L + 3 S + 5 W = 12 LA



You are given 9 cups of lemon juice (L), 8 cups of sugar (S) and unlimited water (W).



Which ingredient limits (runs out first) the amount of lemonade you can make?

Question 2 options:

Lemon Juice


Sugar


Water


Lemonade

Question 3
You are making lemonade and the calls for 6 cups Lemon juice (L), 3 Cups of sugar (S) and 5 cups of water (W) to make 12 Cups of Lemonade (LA): your formula is:



6 L + 3 S + 5 W = 12 LA



You are given 9 cups of lemon juice (L), 8 cups of sugar (S) and unlimited water (W).



How much of the other ingredient do you have in excess (more then you need)? (don’t include water since you have an unlimited amount)

Question 3 options:

4.5 cups of Sugar


3.5 cups of Sugar


3.5 cups of lemon juice


4.5 cups of lemon juice

Answers

Answer:

1.) 12 tablespoons of sugar and 3 cups of water (48 tablespoons)

2.) Amount of lemon juice, sugar and water required will be = 0.375 cups, 0.75 cups and 3 cups.

Step-by-step explanation:

Malanie is making lemonade and finds a recipe that requires lemon juice, sugar and water in the ratio of 1 : 2 : 8.

She juices 2 lemons to obtain 6 tablespoons of lemon juice.

∵ 16 tablespoons = 1 cup

∴ 1 tablespoon =  cup

∴ 6 tablespoon =   cup =  0.375 cups

Since ratio between lemon and sugar is 1 : 2

So amount of sugar required = 0.375×2 = 0.75 cups

Ratio between lemon and water is 1 : 8

So amount of water required = 0.375×8 = 3 cups

Therefore, amount of lemon juice, sugar and water required = 0.375 cups, 0.75 cups sugar and 3 cups respectively.

Explanation:

Answer:

18 cups.

Lemon Juice

I put 4.5 cups of sugar

I got 4/5 on this quiz and I don't remember which was wrong but there you go...

Which of the following increases the concentration of OH- ions?
A: Acid
B: Base
C: Water
D: Salt ​

Answers

Answer:

Basee is the answer hope its write xd

Answer:

B: Base

Explanation:

An acid will increase the concentration of hydrogen (H+) ions in a solution, and a base would increase the concentration of hydroxide (OH–) ions in a solution. So, Base is the answer.  :)

What element is this atom?
(Urgent plz help)

Answers

i’m pretty sure it is Argon

In a polar covalent bond, the more electronegative atom pulls electrons closer and gains a slightly _______ charge, while the less electronegative atom has a slightly _________ charge.

Answers

Answer:

In a polar covalent bond, the more electronegative atom pulls electrons closer and gains a slightly negative charge, while the less electronegative atom has a slightly positive charge.

Explanation:

The covalent bond is the chemical bond between two atoms where electrons are shared. This makes the atoms behave as a unit, which we call a molecule. Atoms interact with each other through the outermost electrons forming bonds.

In other words, the covalent bond is formed by sharing a pair of electrons between the two atoms, one coming from each atom. The shared pair of electrons is common to the two atoms and holds them together. So molecules are formed: small groups of atoms linked together by covalent bonds.

In covalent bonds a dipole forms. The atom with the highest electronegativity attracts electrons towards itself, forming a negative dipole around it since the electrons have a negative charge. In the atom with lower electronegativity, the dipole formed is positively charged, since it partially gives up its electrons.

This is, in a polar covalent bond, the more electronegative atom pulls electrons closer and gains a slightly negative charge, while the less electronegative atom has a slightly positive charge.

Use what you know about endothermic and exothermic reactions to explain the differences in the graphs above

Answers

Answer:

yes I do

But I can't see the question very well

Explanation:

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