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Sholpan [36]
3 years ago
6

Which are exmaples of chemical change?

Chemistry
1 answer:
aniked [119]3 years ago
5 0

Answer:

C: salt is dissolved into freshwater

D: salt is dissolved into freshwater

F: frying changes the color and texture of an egg

G: ocean water evaporates to water vapor on a hot day

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1. Review the information in the table below. Use the information to calculate rate of how many sandwiches are made in a 10-minu
PilotLPTM [1.2K]

Answer:

The answer to your question is given below.

Explanation:

Rate is simply defined as quantity per unit time. Mathematically it is represented as:

Rate = Quantity /time

Thus, we can obtain the rate as follow:

1. Quantity = 20 sandwich

Time = 10 mins

Rate =?

Rate = Quantity /time

Rate = 20/10

Rate = 2 sandwich per mins

2. Quantity = 30 sandwich

Time = 10 mins

Rate =?

Rate = Quantity /time

Rate = 30/10

Rate = 3 sandwich per mins

3. Quantity = 40 sandwich

Time = 10 mins

Rate =?

Rate = Quantity /time

Rate = 40/10

Rate = 4 sandwich per mins

4. Quantity = 50 sandwich

Time = 10 mins

Rate =?

Rate = Quantity /time

Rate = 50/10

Rate = 5 sandwich per mins

Thus, the complete table is given as follow:

Quantity >> Unit of measure >> Rate

10 >>>>>>> 10 min >>>>>>>>>> 1

20 >>>>>>> 10 min >>>>>>>>>> 2

30 >>>>>>> 10 min >>>>>>>>>> 3

40 >>>>>>> 10 min >>>>>>>>>> 4

50 >>>>>>> 10 min >>>>>>>>>> 5

4 0
3 years ago
The molar heat capacity of an unknown substance is 92.1 J/mol-K. If the unknown has a molar mass of 118 g/mol, what is the speci
dlinn [17]

Answer : The specific heat (J/g-K) of this substance is, 0.780 J/g.K

Explanation :

Molar heat capacity : It is defined as the amount of heat absorbed by one mole of a substance to raise its temperature by one degree Celsius.

1 mole of substance releases heat = 92.1 J/K

As we are given, molar mass of unknown substance is, 118 g/mol that means, the mass of 1 mole of substance is, 118 g.

As, 118 g of substance releases heat = 92.1 J/K

So, 1 g of substance releases heat = \frac{92.1}{118}=0.780J/g.K

Thus, the specific heat (J/g-K) of this substance is, 0.780 J/g.K

8 0
3 years ago
Three Stoichiometry Questions
andrezito [222]

Answer:

Explanation:

7)

Given data:

Mass of aluminium = 2.5 g

Mass of oxygen = 2.5 g

Mass of aluminium oxide = 3.5 g

Percent yield = ?

Solution:

Chemical equation:

4Al + 3O₂   →   2Al₂O₃

Number of moles of Al:

Number of moles = mass/ molar mass

Number of moles = 2.5 g/ 27 g/mol

Number of moles = 0.09 mol

Number of moles of oxygen:

Number of moles = mass/ molar mass

Number of moles = 2.5 g/ 32 g/mol

Number of moles = 0.08 mol

Now we will compare the moles of aluminium oxide with aluminium and oxygen.

                          Al         ;       Al₂O₃

                           4         :        2

                        0.09      :       2/4×0.09 = 0.045

                          O₂       :        Al₂O₃

                          3         :          2

                         0.08    :        2/3 ×0.08 = 0.053

The number of moles of aluminium oxide produced by Al are less so it will limiting reactant.

Mass of aluminium oxide:

Mass = number of moles × molar mass

Mass = 0.045  × 101.96 g/mol

Mass = 4.6 g

Percent yield:

Percent yield = actual yield / theoretical yield ×100

Percent yield = 3.5 g / 4.6 ×100

Percent yield = 76.1%

8)

Given data:

Mass of copper produced = 3.47 g

Mass of aluminium = 1.87 g

Percent yield = ?

Solution:

Chemical equation:

2Al + 3CuSO₄   →   Al₂(SO₄)₃ + 3Cu

Number of moles of Al:

Number of moles = mass/ molar mass

Number of moles = 1.87 g/ 27 g/mol

Number of moles = 0.07 mol

Now we will compare the moles of copper with aluminium.

                          Al         ;       Cu

                           2         :        3

                        0.07      :       3/2×0.09 = 0.105

             

Mass of copper:

Mass = number of moles × molar mass

Mass = 0.105  × 63.55 g/mol

Mass = 6.67 g

Percent yield:

Percent yield = actual yield / theoretical yield ×100

Percent yield =  3.47 g / 6.67 × 100

Percent yield = 52%

                       

4 0
3 years ago
The Kinetic Molecular Theory (KMT) is discussed in this lesson, and it helps us understand the behavior of gases. From what we l
kiruha [24]

Answer:

B

Explanation:

The average kinetic energy of the particles of gases is directly proportional to the absolute temperature in kelvin and all gases at the same temperature have the same average kinetic energy, it not  that average energy of the particles is dependent on the molecular mass of the particle.

5 0
3 years ago
Why does sawdust burn faster than logs.
Scilla [17]

Answer:

B. Smaller Particles

Explanation:

We know that the rate of reaction increases with increase in the surface area of reactants.

The reacting particles in the log of wood are embedded inside the wood making only very minimal amount of particles available for reaction. This  ultimately slows down the rate of combustion.

However, in saw dust, there is a greater availability of surface area of reactants hence the sawdust burns faster than logs.

7 0
3 years ago
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