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3 years ago

Which scenarios are examples of physical changes? Check all that apply.

Chemistry

2 answers:

lawyer [7]3 years ago

8 0

Explanation:

Physical change is a change that does not affect the chemical composition of a substance but it changes the physical appearance like size or shape of the substance.

For example, crushing a can, melting of ice, breaking a glass etc represents the physical change.

Scenarios which represent examples of physical changes are as follows.

Silicon is cut into tiny pieces for computer chips.
Lead is melted to form pellets.
Liquid water freezes to form ice.

Alona [7]3 years ago

3 0

Answer:

Lead is melted to form pellets

Explanation:

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You are trying to determine the volume of the balloon needed to match the density of the air in the lab. You know that if you ca

vova2212 [387]

The equation to be used are:

PM = ρRT
PV = nRT
where
P is pressure, M is molar mass, ρ is density, R is universal gas constant (8.314 J/mol·K), T is absolute temperature, V is volume and n is number of moles

The density of air at 23.5°C, from literature, is 1.19035 kg/m³. Its molar mass is 0.029 kg/mol.

PM = ρRT
P(0.029 kg/mol) = (1.19035 kg/m³)(8.314 J/mol·K)(23.5+273 K)
P = 101,183.9 Pa

n = 0.587 g * 1 kg/1000 g * 1 mol/0.029 kg = 0.02024 mol
(101,183.9 Pa)V = (0.02024 mol)(8.314 J/mol·K)(23.5+273 K)
Solving for V,
V = 4.931×10⁻⁴ m³
Since 1 m³ = 1000 L
V = 4.931×10⁻⁴ m³ * 1000
V = 0.493 L

7 0

3 years ago

Just as the depletion of stratospheric ozone today threatens life on Earth today, its accumulation was one of the crucial proces

inessss [21]

Answer:

(a) rate = -(1/3) Δ[O₂]/Δt = +(1/2) Δ[O₃]/Δt

(b) Δ[O₃]/Δt = 1.07x10⁻⁵ mol/Ls

Explanation:

By definition, the reaction rate for a chemical reaction can be expressed by the decrease in the concentration of reactants or the increase in the concentration of products:

aX → bY (1)

$rate= -\frac{1}{a} \frac{\Delta[X]}{ \Delta t} = +\frac{1}{b} \frac{\Delta[Y]}{ \Delta t}$

where, a and b are the coefficients of de reactant X and product Y, respectively.

(a) Based on the definition above, we can express the rate of reaction (2) as follows:

3O₂(g) → 2O₃(g) (2)

$rate = -\frac{1}{3} \frac{\Delta[O_{2}]}{\Delta t} = +\frac{1}{2} \frac{ \Delta[O_{3}]}{ \Delta t}$ (3)

(b) From the rate of disappearance of O₂ in equation (3), we can find the rate of appearance of O₃:

$rate = +\frac{1}{2} \frac{\Delta[O_{3}]}{ \Delta t} = -\frac{1}{3} \frac{\Delta[O_{2}]}{ \Delta t}$

$+\frac{\Delta[O_{3}]}{ \Delta t} = -\frac{2}{3} \frac{\Delta[-1.61 \cdot 10^{-5}]}{ \Delta t}$

$\frac{\Delta[O_{3}]}{ \Delta t} = 1.07 \cdot 10^{-5} \frac{mol}{Ls}$

So the rate of appearance of O₃ is 1.07x10⁻⁵ mol/Ls.

Have a nice day!

6 0

4 years ago

The octet rule is the basis for the stability of the atom. According to this rule, the outermost shell of the atom must contain

liubo4ka [24]

Answer:8

Explanation:

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3 years ago

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VMariaS [17]

Gravitational kinetic

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3 years ago

If the density of a substance is 15g/ml what would the volume be if it has a mass of 10g?

Zolol [24]

Answer:

the answer would be 0.666 mL

Explanation:

10g is 66% of 15g

6 0

3 years ago