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3 years ago

Which sample of matter can be seperated into different substances by physical means

1 answer:

8 0

A mixture of matter. A mixture consists of two or more elements physically combined. Take salt water. It is a mixture. So just evaporate the salt water to dryness, it would be separated into salt and water. Hence, mixture can be separatedinto different substances by physical means. You can also use magnet.

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Why do scientific theories change?

Sergio039 [100]

Scientific theories change because theories may be modified or overturned as new evidence and perspective emerges. ... The process of theory change may take time and involve controversy, but eventually the scientific explanation that is more accurate will be accepted. Hoped you get it!

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2 years ago

Read 2 more answers

Five solutions on how to prevent air pollution

I am Lyosha [343]

Answer:

Reduce number of trips

Avoid burning leaves

Avoid using garden equipments

Reduce the use of wood stove

Avoid gas-powered lawn.

Explanation:

7 0

3 years ago

At a certain temperature the vapor pressure of pure chloroform (CHCl3) is measured to be 91. torr. Suppose a solution is prepare

OleMash [197]

Answer:

$P_{CCl_4}=52.43torr$

Explanation:

Hello there!

In this case, sine the solution of this problem require the application of the Raoult's law, assuming heptane is a nonvolatile solute, so we can write:

$P_{CCl_4}=x_{CCl_4}P_{CCl_4}^{vap}$

Thus, we first calculate the mole fraction of chloroform, by using the given masses and molar masses as shown below:

$x_{CCl_4}=\frac{140/153.81}{140/153.81+67.1/100.21}=0.576$

Therefore, the partial pressure of chloroform turns out to be:

$P_{CCl_4}=0.576*91torr\\\\P_{CCl_4}=52.43torr$

Regards!

3 0

3 years ago

Calculate the molarity of a solution obtained dissolving 10.0 g of cobalt(Ⅱ) bromide tetrahydrate in enough water to make 450 mL

Vladimir [108]

Answer:

The molarity of the CoBr2•4H2O solution is 7.64 × 10-2 M

Explanation:

Cobalt (II) bromide tetrahydrate

• Cobalt - A transition metal with Roman numeral (II) → charge: +2 → Co2+

• Bromide - anion from group 7A → -1 charge → symbol: Br-

• Tetrahydrate- tetra- means 4 and hydrate is H2O

The chemical formula of the compound is: CoBr2•4H2O

We then need to determine the number of moles of CoBr2•4H2O since this is the only information missing for us to find molarity. Notice that the volume of the solution is already given.

We’re given the mass of CoBr2•4H2O. We can use the molar mass of CoBr2•4H2O4 to find the moles.

•The molar mass of CoBr2•4H2O is:

CoBr2•4H2O

1 Co x 58.93 g/mol Co = 58.93 g/mol

2 Br x 79.90 g/mol Br = 159.80 g/mol

8 H x 1.008 g/mol H = 8.064 g/mol

4 O x 16.00 g/mol O = 64.00 g/mol

________________________________________

Sum = 290.79 g/ mo

The moles of CoBr2•4H2O is:

= 10.0 g CoBr2•4H2O x $\frac{ 1 mol CoBr_2 . 4H_2O}{290.79 g CoBr_2 . 4H_2O}$

= 0.0344 mol CoBr2•4H

We know that the volume of the solution is 450 mL.

We can now calculate for molarity:

Convert mL to L → 1 mL = 10-3 L

Formula:

Molarity (M)= Mole of solute / Liters of solution

= 0.0344 mol CoBr2•4H / 450 mL x 1 ml / 10^ -3 L

= 0.0764

= 7.64 × 10-2 mol/L

8 0

3 years ago

A Flame test is an example of chemistry property. What evidence can you use to back your statement up?

Lena [83]

The flame test is a qualitative test used in chemistry to help determine the identity or possible identity of a metal or metalloid ion found in an ionic compound. If the compound is placed in the flame of a gas burner, there may be a characteristic color given off that is visible to the naked eye. And for the proof. The flame test provided evidence that specific atoms are present in compounds by the color of the flame. The metal atoms are what is responsible for the colors during the flame test. The color of the flame will be yellow-orange because Sodium (Na) is present in all the compounds that have a yellow-orange flame. Hope this helps! Mark brainly please!

7 0

2 years ago