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3 years ago

When you blow dry your hair

2 answers:

4 0

Any change that occurs without altering the chemical composition of a substance is a physical change. Physical changes can include changing the color, shape, state of matter, or volume of a substance
A usually irreversible chemical reaction involving the rearrangement of the atoms of one or more substances and a change in their chemical properties or composition, resulting in the formation of at least one new substance: The formation of rust on iron is a chemical change.

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Physical
Chemical
Chemical
Chemical
Chemical
Chemical

mixer [17]3 years ago

3 0

In short a physical change is something that changed the way something looks but doesn't affect the chemical makeup. Drying your hair doesn't change the color of your hair, it just makes it dry so thats a physical change. Rust forming on a knife is a chemical change becaause the water reacts with the chemical makeup of the knife. Hope that helps.

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Chemical bonding for <br><br> Rb & nitrogen,<br><br> Need help!!!

LekaFEV [45]

Covalent bonding!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

5 0

3 years ago

If 16.9 kg of Al2O3(s), 57.4 kg of NaOH(l), and 57.4 kg of HF(g) react completely, how many kilograms of cryolite will be produc

hodyreva [135]

Answer: 69.72 kg of cryolite will be produced.

Explanation:

The balanced chemical equation is:

$Al_2O_3(s)+6NaOH(l)+12HF(g)\rightarrow 2Na_3AlF_6+9H_2O$

To calculate the moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text {Molar mass}}$

moles of $Al_2O_3$ = $\frac{16.9\times 1000g}{102g/mol}=165.7moles$

moles of $NaOH$ = $\frac{57.4\times 1000g}{40g/mol}=1435moles$

moles of $HF$ = $\frac{57.4\times 1000g}{20g/mol}=2870moles$

As 1 mole of $Al_2O_3$ reacts with 6 moles of $NaOH$

166 moles of $Al_2O_3$ reacts with = $\frac{6}{1}\times 166=996$ moles of $NaOH$

As 1 mole of $Al_2O_3$ reacts with 12 moles of $HF$

166 moles of $Al_2O_3$ reacts with = $\frac{12}{1}\times 166=1992$ moles of $HF$

Thus $Al_2O_3$ is the limiting reagent.

As 1 mole of $Al_2O_3$ produces = 2 moles of cryolite

166 moles of $Al_2O_3$ reacts with = $\frac{2}{1}\times 166=332$ moles of cryolite

Mass of cryolite $(Na_3AlF_6)$ = $moles\times {\text {molar mass}}=332mol\times 210g/mol=69720g=69.72kg$

Thus 69.72 kg of cryolite will be produced.

8 0

3 years ago

Has anyone ever done something they weren't proud of at the time but now when you look back at it then you think like it makes y

ludmilkaskok [199]

Answer:

uhm no sadly

Explanation:

Typically, they prepare the patient for their dental exam or procedure, sterilize and disinfect instruments, record treatment information, take down medical and dental histories, instruct patients in oral hygiene, order dental supplies, schedule appointments, and create orthodontic appliances.

3 0

3 years ago

Iodine is prepared both in the laboratory and commercially by adding Cl2(g) to an aqueous solution containing sodium iodide. 2Na

otez555 [7]

Answer:

79.0 g

Explanation:

1. Gather the information in one place.

MM: 148.89 253.81

2NaI + Cl2 → I2 + 2NaCl

m/g: 67.3

2. Moles of I2

n = 67.3 g × (1 mol/253.81 g) = 0.2652 mol I2

2. Moles of NaI needed

From the balanced equation, the molar ratio is 2 mol NaI: 1 mol I2

n = 0.028 76 mol I2× (2 mol NaI/1 mol I2) = 0.5303 mol NaI

3. Mass of NaI

m = 0.5303 mol × (148.89 g/1 mol) = 79.0 g NaI

It takes 79.0 g of NaI to produce 67.3 g of I2.

6 0

4 years ago

A region of metamorphic rock lies far beneath Earth’s surface. In time, which two ways can the rock make its way upward to Earth

NeX [460]

It can uplift slowly due to the pressure of Earth’s plates.

It can melt into magma and recrystallize as extrusive igneous rock.

8 0

4 years ago

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