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3 years ago

When cream mixes with coffee, is this a chemical or physical change?

1 answer:

7 0

It is a physical change when cream mixes with coffee, it changes the color of the coffee. When you add more or less cream there is a color change depending on the consistency of cream. The properties are not changes and a no new compound is formed as in chemical change with a reaction of two compounds, a new compound is formed with different properties. So it is a physical change.

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23) What is the volume of 2.454 x 1024 atoms of nitrogen gas at STP?

earnstyle [38]

Answer:

d) V = 91.3 L

Explanation:

Given data:

Volume of nitrogen = ?

Temperature = standard = 273.15 K

Pressure = standard = 1 atm

Number of atoms of nitrogen = 2.454×10²⁴ atoms

Solution:

First of all we will calculate the number of moles of nitrogen by using Avogadro number.

1 mole = 6.022×10²³ atoms

2.454×10²⁴ atoms × 1 mol / 6.022×10²³ atoms

0.407×10¹ mol

4.07 mol

Volume of nitrogen:

PV = nRT

1 atm × V = 4.07 mol ×0.0821 atm.L /mol.K ×273.15 K

V = 91.3 atm.L /1 atm

V = 91.3 L

3 0

3 years ago

Na2SO4<br> How many oxygen stems are?

IgorLugansk [536]

Answer:

Na2SO4 means: two moles sodium (45.98 g), one mole sulfur (32.06 g), and four moles oxygen (64.00 g) combine to form one mole of sodium sulfate (142.04 g).

Explanation:

3 0

3 years ago

Read 2 more answers

Need help ASAP!<br><br> How many moles of sodium nitrate are in 0.25 L of 1.2 M NaNO3 solution?

Setler79 [48]

Answer:

$\boxed {\boxed {\sf 0.3 \ mol \ NaNO_3}}$

Explanation:

Molarity is a measure of concentration in moles per liter.

$molarity= \frac{moles \ of \ solute}{liters \ of \ solution}$

The molarity of the solution is 1.2 M NaNO₃ or 1.2 moles NaNO₃ per liter. There are 0.25 liters of the solution. The moles of solute are unknown, so we can use x.

molarity= 1.2 mol NaNO₃/L
liters of solution=0.25 L
moles of solute =x

$1.2 \ mol \ NaNO_3/L= \frac{x}{0.25 \ L}$

We are solving for x, so we must isolate the variable, x. It is being divided by 0.25 liters. The inverse of division is multiplication, so we multiply both sides by 0.25 L.

$0.25 \ L *1.2 \ mol \ NaNO_3/L=\frac{x}{0.25 \ L} *0.25 \ L$

$0.25 \ L *1.2 \ mol \ NaNO_3/L=x$

The units of liters cancel, so we are left with the units moles of sodium nitrate.

$0.25 *1.2 \ mol \ NaNO_3=x$

$0.3 \ mol \ NaNO_3=x$

There are 0.3 moles of sodium nitrate.

3 0

2 years ago

According to Wookieepedia, Kylo Ren stands 1.89 m tall and his mass is 89 kg. Calculate his earth-weight in lbm. (2 pts) a. b. A

harina [27]

Answer:

a) 6312.12 lbm

b) D = 11.843 inch

Explanation:

GIVEN DATA:

Height of person = 1.89 m = 74.41 inch

mass of person m = 89 kg = 196.211 lbm

a) person earth weight =mg

where g is acceleration due to gravity = 32.17 ft/sec^2

$= 196.211\times 32.17 = 6312.12 lbm$

b) waist to height ratio = 0.5

$waist\ to\ height\ ratio = \frac{circumference\ of\ the\ waist}{height\ of\ the\ person}$

circumference of waist = $height\ of\ person \times waist\ to\ height ratio$

$= 74.41 inch \times 0.5$

=37.21 inch

we know that circumference is given as $= 2\pi r\ or\ \pi D= 37.21$

D = 11.843 inch

6 0

3 years ago

Which solution has the higher boiling point?

dedylja [7]

NaCl has higher boiling point than C₂H₆O₂ in H₂O.

<h3>What is molality?</h3>

The number of moles of solute in a solution equal to 1 kg or 1000 g of solvent is referred to as its molality.
The definition of molarity, on the other hand, is based on a certain volume of solution.
Mol/kg is a typical molality measurement unit in chemistry.

<h3>Calculation of boiling point:</h3>

When the non-volatile solute is dissolved in a solvent, the boiling point rises along with the molality (concentration) of the solute.

Given,

Mass of C₂H₆O₂ (solute) = 15.0 g

Mass of solvent (H₂O) = 0.50 kg

Molar mass of C₂H₆O₂ = 62 g/mol

Thus, the moles of solute = 15.0 g x 1.0 mol solute/62 g/mol

= 0.2419 mol

Therefore, molality(m) of C₂H₆O₂ (solute) = Amount of solute (mol)/ Mass of solvent

= 0.2419/0.50

= 0.4838 m

Similarly,

Given ,

Mass of NaCl (solute) = 15 g

Mass of solvent (H₂O) = 0.50 kg

Molar mass of NaCl (solute) = 58.44 g/mol

Thus, the moles of NaCl (solute) = 15.0 g x 1.0 mol solute/58.44

= 0.2566 mol

Therefore, molality(m) of NaCl (solute) = Amount of solute (mol)/ Mass of solvent

= 0.2566 mol/0.50 kg

= 0.51 m

Hence, the molality of NaCl (solute) is more than the molality of C₂H₆O₂(solute).

So, with an increase in the solute's concentration (molality), the boiling point rises.

Therefore, NaCl has higher boiling point than C₂H₆O₂ in H₂O.

Learn more about boiling point here:

brainly.com/question/24168079

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7 0

2 years ago