1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Leviafan [203]
2 years ago
11

A friend tells you, because composition does not change during a physical changes, the appearance of a substance does not change

. is your friend correct? explain why.
Chemistry
1 answer:
Travka [436]2 years ago
3 0
That friend is not correct. Physical change is characterized by a change in appearance without any change in composition. So, if the appearance did not change in the situation, then there is no change in the system. This type of change affects the form of a substance but not the composition or the structure of the molecules. Examples of this type of change are ice melting, cutting a paper into half, clay is molded to a new shape, butter melting, water evaporating. The change that involves a change in chemical composition is classified a chemical change. In this type of change, chemical reactions would take place.
You might be interested in
Potassium iodide reacts with lead(II) nitrate in this precipitation reaction: 2 KI(aq) + Pb(NO3)2(aq) → 2 KNO3(aq) + PbI2(s) Wha
andrew11 [14]

Answer:

a. 174 mL

Explanation:

Let's consider the following reaction.

2 KI(aq) + Pb(NO₃)₂(aq) → 2 KNO₃(aq) + PbI₂(s)

We have 155.0 mL of a 0.112 M lead(II) nitrate solution. The moles of Pb(NO₃)₂ are:

0.1550 L × 0.112 mol/L = 0.0174 mol

The molar ratio of KI to Pb(NO₃)₂ is 2:1. The moles of KI are:

2 × 0.0174 mol = 0.0348 mol

The volume of a 0.200 M KI solution that contains 0.0348 moles is:

0.0348 mol × (1 L / 0.200 mol) = 0.174 L = 174 mL

5 0
2 years ago
The coefficient of performance (cop) of a refrigerator is defined as the ratio of?
Vinvika [58]

The coefficient of performance (cop) of a refrigerator is defined as the ratio of " the work necessary to heat or cool something usefully."

The usable heating or cooling delivered to work required ratio, also known as the coefficient of performance, or COP, of a heat pump, refrigerator, as well as air conditioning system. Higher efficiency, less energy (power) usage, and thus reduced operational costs are all related to higher COPs.

Coefficient of performance formula:

K = Q_{H} / W_{in}

where, K = Coefficient of performance, Q_{H} = heat of pumps output, W_{in} = work required by the system.

It is refrigeration's coefficient of performance (COP) will always be greater than 1.

Therefore, the coefficient of performance (cop) of a refrigerator is defined as the ratio of " the work necessary to heat or cool something usefully."

To know more about  coefficient of performance

brainly.com/question/14058512

#SPJ4

3 0
1 year ago
Correction?
rjkz [21]
Your answer is correct.

MgO(s) + H2O(l) ----> Mg(OH)2(aq)

:-) ;-)
5 0
2 years ago
Read 2 more answers
A sample of air is slowly passed through aqueous Sodium hydroxide and then over heater copper. Which gases are removed by this p
bagirrra123 [75]

Carbon dioxide and oxygen are removed from the air.

Explanation:

When air is passed through aqueous sodium hydroxide solution the carbon dioxide is removed from the air.

First the carbon dioxide will dissolve and react with water to form carbonic acid ( H₂CO₃) :

CO₂ + H₂O → H₂CO₃

The the carbonic acid will react with sodium hydroxide to form sodium carbonate (Na₂CO₃):

H₂CO₃ + 2 NaOH → Na₂CO₃ + 2 H₂O

After this by passing the air over heated cooper the oxygen is removed.

2 Cu + O₂ → 2 CuO

Learn more about:

neutralization reaction

brainly.com/question/2632201

#learnwithBrainly

7 0
3 years ago
each of the following reactions has been reported in the chemical literature. predict the product in each case, showing stereoch
poizon [28]

(a): This is an elimination reaction. The reaction proceeds in 3 steps; Step 1: Protonation of alcohol, step 2: Loss of leaving group, and step 3: Deprotonation to form an alkene. Elimination (E1) reaction dominates than substitution (SN1) reaction because the formed HSO4- anion is a poor nucleophile and tends not to add to the carbocation intermediate formed. Hence the product formed is I, is trans.

(b) This is a dihydroxylation of the alkenes reaction. A catalytic amount of OsO4 is used along with an oxidizing agent, which oxidizes the reduced osmium(VI) into osmium(VIII) to regenerate the catalyst. The reaction proceeds in 2 steps; Step 1: Cis addition of OsO4 to double bond and form 4 member cyclic osmate ester. Step 2: Hydrolysis of the intermediate to 1.2-diol. Hence the product formed is II, is cis. 

(c) This is hydroboration - oxidation reaction. The reaction proceeds through the addition of H- on the more substituted carbon and BH2 on the less substituted carbon of the double bond. The reaction is a syn addition. Hence the product formed is III.

(d) This a reduction reaction where carboxylic acid (-COOH) is reduced to 1o alcohol (-CH2OH). Hence the formed product is IV.

Stereochemistry, a subdiscipline of chemistry, involves the take a look at the relative spatial association of atoms that form the shape of molecules and their manipulation.

The observation of stereochemistry specializes in stereoisomers, which by means of definition have an equal molecular method and series of bonded atoms (constitution), however, differ within the three-dimensional orientations of their atoms in space. for that reason, it's also referred to as 3-d chemistry three-dimensionality.

Learn more about  Stereochemistry here:-brainly.com/question/13266152

#SPJ4

<u>Disclaimer:- your question is incomplete, please see below for the complete question.</u>

Each of the following reactions has been reported in the chemical literature. Predict the product in each case, showing stereochemistry where appropriate.

5 0
8 months ago
Other questions:
  • When ice melts what happens to the water molecules
    7·1 answer
  • What is white light?
    11·2 answers
  • N=?
    6·1 answer
  • Which of these are true for a hypothesis? (You can pick more than one)
    13·1 answer
  • 1.2 dkg to grams now I have to say extra stuff for it to submit
    6·1 answer
  • Anyone please help I’m in summer school please
    13·1 answer
  • Calculate the number of molecules in 100. g of O2 *
    6·1 answer
  • In which of these situations should a fire blanket be used?
    10·2 answers
  • Give reasons.
    8·2 answers
  • What is one way humans can control landfills?
    6·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!