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KatRina [158]
2 years ago
7

7th grade science can anyone help

Chemistry
1 answer:
Assoli18 [71]2 years ago
4 0
You need to put a question in order for people to answer
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can someone explain how this is wrong? I don’t think it is wrong but my chem teacher deducted points. so why?
ruslelena [56]

Answer: measure the mass (48.425g) of KCl

Explanation:

To prepare the solution 0.65M KCl we must measure the mass of KCl that would be dissolved in 1L of the solution. This can be achieved by:

Molar Mass of KCl = 39 + 35.5 = 74.5g/mol

Number of mole (n) = 0.65

Mass conc of KCl = n x molar Mass

Mass conc of KCl = 0.65 x 74.5 = 48.425g

Therefore, to make 0.65M KCl, we must measure 48.425g

7 0
3 years ago
Can pure substances made from compounds be physically separated?
Arisa [49]

Answer:

it cannot !!

Explanation:

a chemical reaction MUST occur to separate a compound! :)

4 0
3 years ago
Consider the equation: 2NO(0) - N.04(). Using ONLY the information given by the equation which of the following
ratelena [41]

Answer:

By increasing the pressure, the molar concentration of  N2O4 will increase

Explanation:

We have the equation 2NO2 ⇔ N2O4

This equation is reversible and exotherm. By <u>decreasing the temperature</u>, the reaction will produce more energy, so the reaction will move to the right.  But a lower temperature also lowers the rate of the process, so, the temperature is set at a compromise value that allows N2O4 to be made at a reasonable rate with an equilibrium concentration that is not too unfavorable

So <u>increasing the temperature</u> will shift the equilibrium to the left. The equilibrium shifts in the direction that consumes energy.

If we d<u>ecrease the concentration of NO2</u>, the equilibrium will shift to the left, resulting in forming more reactants.

To increase the molar concentration of the product N2O4, we have to <u>increase the pressure</u> of the system.

NO2 takes up more space than N2O4, so increasing the pressure would allow the reactant to collide more form more product.

By increasing the pressure, the molar concentration of  N2O4 will increase

7 0
3 years ago
Read 2 more answers
Which of the following is a statement of Hess's law?
attashe74 [19]

Answer:

C

Explanation:

the enthalpy of reaction is independent of the reaction path

7 0
2 years ago
Which of the following changes can alter the form of a substance but does not necessarily change it to an other substance?
Goshia [24]

Answer:

  • The physical changes can alter the form of a substance but does not necessarily change it to an other substance

Explanation:

  • The physical properties of matter is one that does not depend on composition.It just change the form of matter into another form with changing into composition.
  • Physical properties include: appearance, texture, color, odor, melting point, boiling point, density, solubility, polarity, and many others.
  • The three states of matter are: solid, liquid, and gas. The melting point and boiling point are related to changes of the state of matter. All matter may exist in any of three physical states of matter.

Example:

  1. When water is boiled then it change into vapors. Now the form of water is change but its composition is same like water
  2. When water freezes into ice, now phase are different i.e water is liquid while ice is solid but both have same composition.
8 0
3 years ago
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