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3 years ago

Melting butter is a physical change. Which best describes what is happening?

2 answers:

5 0

The butter contains a new arrangement of atoms. It’s a physical change therefore it cannot change into a different substance and it can turn into a solid again as physical changes just the property of a substance. The butter also remains as butter so there would still be the same number of atoms.

vlabodo [156]3 years ago

4 0

Melting butter is a physical change. The statement that best describes what is happening is that the butter contains a new arrangement of atoms.

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What is a proper adjective?

Alex17521 [72]

This is what a proper adjective is.

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3 years ago

A 25.0 mL sample of a saturated C a ( O H ) 2 solution is titrated with 0.029 M H C l , and the equivalence point is reached aft

Gnesinka [82]

Answer:

0.043 M

Explanation:

The reaction that takes place is:

Ca(OH)₂ + 2HCl → CaCl₂ + 2H₂O

First we calculate how many HCl moles reacted, using the given concentration and volume required to reach the equivalence point:

0.029 M HCl * 37.3 mL = 1.0817 mmol HCl = 1.0817 mmol H⁺

As 1 mol of H⁺ reacts with 1 mol of OH⁻, in the 25.0 mL of the Ca(OH)₂ sample there are 1.0817 mmoles of OH⁻.

With that in mind we can calculate the hydroxide ion concentration in the original sample solution, using the calculated number of moles and given volume:

1.0817 mmol OH⁻ / 25.0 mL = 0.043 M

3 0

3 years ago

A sodium hydroxide solution is made by mixing 8.70 g NaOH with 100 g of water. The resulting solution has a density of 1.087 g/m

Ahat [919]

Answer:

Mass fraction = 0.08004

Mole fraction = 0.0377

Explanation:

Given, Mass of NaOH = 8.70 g

Mass of solution = 8.70 + 100 g = 108.70 g

$Mass\ fraction\ of\ NaOH=\frac {8.70}{108.70}$ = 0.08004

Molar mass of NaOH = 39.997 g/mol

The formula for the calculation of moles is shown below:

$moles = \frac{Mass\ taken}{Molar\ mass}$

Thus,

$Moles= \frac{8.70\ g}{39.997\ g/mol}$

$Moles\ of\ NaOH= 0.2175\ mol$

Given, Mass of water = 100 g

Molar mass of water = 18.0153 g/mol

The formula for the calculation of moles is shown below:

$moles = \frac{Mass\ taken}{Molar\ mass}$

Thus,

$Moles= \frac{100\ g}{18.0153\ g/mol}$

$Moles\ of\ water= 5.5508\ mol$

So, according to definition of mole fraction:

$Mole\ fraction\ of\ NaOH=\frac {n_{NaOH}}{n_{NaOH}+n_{water}}$

$Mole\ fraction\ of\ NaOH=\frac {0.2175}{0.2175+5.5508}=0.0377$

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Answer:

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nekit [7.7K]

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3 years ago

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