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Ira Lisetskai [31]
3 years ago
11

What is the density of 19.2 g of oak that has a volume of 25.7 cm3?

Chemistry
1 answer:
andreyandreev [35.5K]3 years ago
7 0

Density = Mass/Volume

19.2/25.7

= 0.747 or 0.75

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What is a Newton?<br> explain please
Lina20 [59]

Answer:

it is the unit of Force

Explanation:

force is equal to Newton

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Will ice melt faster with a lot of salt added or little salt added?
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alot

Explanation:

because salt contains stuff

5 0
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Explain what a chemical reaction is and moles
Delvig [45]

Answer:

A process during which chemical bonds between atoms are broken and new ones are formed, producing one or more substances.

Moles are the amount of substance that contains as many particles.

Explanation:

A chemical reaction is when a chemical change occurs for example when a nail comes into contact with air and is then exposed to air it begins to rust. It forms a red-brown substance which changes the chemical composition of the original compound.

Examples of chemical reactions:

Combustion

Oxidation (rusting)

Cooking an egg

Photosynthesis

Digestion

Fireworks

Paper Burnin

The mole is the amount of substance that contains as many particles (molecules, ions or atoms) as there are in 12g of carbon.

1 mol is the amount of substance that contains the same number of particles as there are atoms in 12.0 g of carbon-12 and that number is referred to as Avogardo's constant (6.022 x 10^{23}).

3 0
2 years ago
A 1.87 L aqueous solution of KOH contains 155 g of KOH . The solution has a density of 1.29 g/mL . Calculate the molarity ( M ),
lbvjy [14]

Answer:

[KOH] = 1.47 M

[KOH] = 1.22 m

KOH = 6.86 % m/m

Explanation:

Let's analyse the data

1.87 L is the volume of solution

Density is 1.29 g/mL → Solution density

155 g of KOH → Mass of solute

Moles of solute is (mass / molar mass) = 2.76 moles.

Molarity is mol/L → 2.76 mol / 1.87 L = 1.47 M

Let's determine, the mass of solvent.

Molality is mol of solute / 1kg of solvent

We can use density to find out the mass of solution

Mass of solution - Mass of solute = Mass of solvent

Density = Mass / volume

1.29 g/mL = Mass / 1870 mL

Notice, we had to convert L to mL, cause the units of density.

1.29 g/mL . 1870 mL = Mass → 2412.3 g

2412.3 g - 155 g = 2257.3 g of solvent

Let's convert the mass of solvent to kg

2257.3 g / 1000 = 2.25kg

2.76 mol / 2.25kg = 1.22 m (molality)

% percent by mass = mass of solute in 100g of solution.

(155 g / 2257.3 g) . 100g = 6.86 % m/m

5 0
3 years ago
The energy E of the electron in a hydrogen atom can be calculated from the Bohr formula:
EleoNora [17]

Answer:

3.89002 × 10 ⁻⁷m = 389.002nm.

Explanation:

Without mincing words let's dive straight into the solution to the problem above. To calculate the wavelength of the line in the absorption line spectrum of hydrogen caused by the transition of the electron from an orbital with n = 2 to an orbital with n = 8, there is the need to make use of the change in energy equation.

The change in energy = 2.18 × 10⁻¹⁸ [ 1/2² - 1/8²] =  2.18 × 10⁻¹⁸ × [0.25 - 0.015625] =  2.18 × 10⁻¹⁸ × 0.234375 = 5.11 × 10⁻¹⁹.  

Therefore, the wavelength = plank's constant × speed of light/ change in energy = 6.626× 10⁻³⁴ × 3 × 10⁸/ 5.11 × 10⁻¹⁹ = 1.9878 × 10⁻²⁵/  5.11 × 10⁻¹⁹ = 0.389002 × 10⁻⁶ = 3.89002 × 10 ⁻⁷m = 389.002nm.

3 0
3 years ago
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