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
Vilka [71]
3 years ago
6

A teacher wants to perform a classroom demonstration that illustrates both chemical and physical changes. Which would be the bes

t demonstration that she could use?
Chemistry
1 answer:
Jlenok [28]3 years ago
5 0

when you crumble paper is still paper when you burn down paper you get ashes. that is want is call chemical and physical changes.

You might be interested in
A 0.500-g sample containing Na2CO3 plus inert matter is analyzed by adding 50.0 mL of 0.100 M HCl, a slight excess, boiling to r
Yakvenalex [24]

The percentage by mass of Na2CO3 in the sample is 48%.

The equation of the reaction of Na2CO3 with HCl;

Na2CO3(aq) + 2HCl(aq) ------> 2NaCl(aq) + H2O(l) + CO2(g)

Since the HCl is in excess, the excess is back titrated with NaOH as follows;

NaOH (aq) + HCl(aq) ---->NaCl(aq) + H2O(l)

Number of moles of HCl added =  0.100 M × 50/1000 L = 0.005 moles

Number of moles of NaOH added = 5.6/1000 ×  0.100 M = 0.00056 moles

Since the reaction of NaOH and NaOH is 1:1, 0.00056 moles of HCl reacted with excess HCl.

Amount of HCl that reacted with Na2CO3 =  0.005 moles -  0.00056 moles = 0.0044 moles

Now;

1 mole of Na2CO3 reacts with 2 moles of HCl

x moles of Na2CO3 reacts with 0.0044 moles of HCl

x = 1 mole × 0.0044 moles / 2 moles

x = 0.0022 moles

Mass of Na2CO3 reacted = 0.0022 moles × 106 g/mol = 0.24 g

Percentage of Na2CO3  in the sample = 0.24 g/ 0.500-g × 100/1 = 48%

Learn more about back titration: brainly.com/question/25485091

5 0
2 years ago
Calculate the mass percent composition for Al(HCO3)3
ZanzabumX [31]

Answer:

salamat sapoints po lods thaks

7 0
2 years ago
The electron in a hydrogen atom, originally in level n = 8, undergoes a transition to a lower level by emitting a photon of wave
timofeeve [1]

Explanation:

It is given that,

The electron in a hydrogen atom, originally in level n = 8, undergoes a transition to a lower level by emitting a photon of wavelength 3745 nm. It means that,

n_i=8

\lambda=3745\ nm

The amount of energy change during the transition is given by :

\Delta E=R_H[\dfrac{1}{n_f^2}-\dfrac{1}{n_i^2}]

And

\dfrac{hc}{\lambda}=R_H[\dfrac{1}{n_f^2}-\dfrac{1}{n_i^2}]

Plugging all the values we get :

\dfrac{6.63\times 10^{-34}\times 3\times 10^8}{3745\times 10^{-9}}=2.179\times 10^{-18}[\dfrac{1}{n_f^2}-\dfrac{1}{8^2}]\\\\\dfrac{5.31\times 10^{-20}}{2.179\times 10^{-18}}=[\dfrac{1}{n_f^2}-\dfrac{1}{8^2}]\\\\0.0243=[\dfrac{1}{n_f^2}-\dfrac{1}{64}]\\\\0.0243+\dfrac{1}{64}=\dfrac{1}{n_f^2}\\\\0.039925=\dfrac{1}{n_f^2}\\\\n_f^2=25\\\\n_f=5

So, the final level of the electron is 5.

4 0
3 years ago
Negatively charged particles within the atom are called what?
Ivahew [28]
Negatively charged particles in atom - Electrons
5 0
3 years ago
____________ is a colorless, odorless gas that forms when fuels are not completely burned.
-Dominant- [34]
Your answer is Carbon monoxide
3 0
3 years ago
Read 2 more answers
Other questions:
  • Explain how following a fitness plan can help you meet a goal
    13·2 answers
  • Is au an atomic element, molecular element, molecular compound or an ionic compound?
    14·1 answer
  • How many moles are in 5.0 x 1025 atoms of iron
    15·1 answer
  • In a eukaryotic cell, in which structure are proteins made?
    6·2 answers
  • A sample of gaseous PCl₅ was introduced into an evacuated flask so that the pressure of pure PCl₅ would be 0.50 atm at 523 K. Ho
    11·1 answer
  • What would be the freezing point of a 1.7 mole aqueous ethylene glycol solution? The freezing point depression constant for wate
    12·1 answer
  • In a bowl of 50 skittles, you have 12 yellow, 9 orange, 11 red, and 13 green. The rest of the skittles are purple. What percenta
    5·1 answer
  • NEED HELP PLSSS
    7·1 answer
  • Please answer this question please brianlest
    15·1 answer
  • ___1___Zn + __2___HCl → ___1___H2 + ____1__ZnCl2
    12·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!