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2 years ago

Is a light bulb chemical or physical change. State evidence why

Chemistry

1 answer:

irakobra [83]2 years ago

8 0

Answer:

It is a chemical change.

Explanation:

When the electricity is off, the filament cools down to its original physical state. This physical process repeats every time the light is turned on and off. However, if the bulb is cracked and air is introduced, the oxygen in the air reacts with the tungsten filament which then undergoes a chemical change.

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You wish to prepare a buffer consisting of acetic acid and sodium acetate with a total acetic acetate plus acetate concentration

vovangra [49]

<u>Ans: Acetic acid = 90.3 mM and Sodium acetate = 160 mM</u>

Given:

Acetic Acid/Sodium Acetate buffer of pH = 5.0

Let HA = acetic acid

A- = sodium acetate

Total concentration [HA] + [A-] = 250 mM ------(1)

pKa(acetic acid) = 4.75

Based on Henderson-Hasselbalch equation

pH = pKa + log[A-]/[HA]

[A-]/[HA] = 10^(pH-pKa) = 10^(5-4.75) = 10^0.25 = 1.77

[A-] = 1.77[HA] -----(2)

From (1) and (2)

[HA] + 1.77[HA] = 250 mM

[HA] = 250/2.77 = 90.25 mM

[A-] = 1.77(90.25) = 159.74 mM

7 0

3 years ago

Which method is suitable for collection a a<br>carbon dioxide.Explain

mel-nik [20]

Answer:

Carbon dioxide can be collected over water. Carbon dioxide is slightly soluble in water and denser than air, so another way to collect it is in a dry, upright gas jar.

Explanation:

8 0

2 years ago

What were the constraints on Nils Bohlin’s solution to safer seatbelts?

ArbitrLikvidat [17]

Answer:

He realized he needs to have the upper body and lower body held in place and needed the buckle as far down beside the person's hip so it could hold the body properly

Explanation: ''I realized both the upper and lower body must be held securely in place with one strap across the chest and one across the hips,'' Mr. Bohlin once said. ''The belt also needed an immovable anchorage point for the buckle as far down beside the occupant's hip, so it could hold the body properly during a collision.

4 0

2 years ago

In a lab experiment, john uses a mesh to separate soil particles from water. Which technique of separation is he using

blondinia [14]

The Filtration techique

5 0

2 years ago

Assuming that a tank of gasoline contains 80 liters and that its density is 0.77 kg/liter, determine how many kg of co2 are prod

sleet_krkn [62]

Answer: -

If a tank of gasoline contains 80 liters and that its density is 0.77 kg/liter, 0.26 kg of CO₂ are produced for each tank of gasoline burned.

Explanation: -

Density of the gasoline = 0.77 kg / liter

Volume of the tank containing the gasoline = 80 liter.

Mass of gasoline produced from each tank

= Volume of the tank containing the gasoline x Density of the gasoline

= $\frac{0.77 kg}{1 liter}$ x 80 liter

= 61.6 kg

Chemical formula of gasoline = C₈H₁₈

Molar mass of gasoline C₈H₁₈ = 12 x 8 + 1 x 18 = 114 g/ mol

Number of moles of C₈H₁₈ = $\frac{61.6 g}{114 g}$ x 1 mol

= 0.54 mol of C₈H₁₈

The chemical equation for the burning of gasoline is

2 C₈H₁₈ + 25 O₂ → 16 CO₂ + 18 H₂O

From the balanced equation we see

2 mol of C₈H₁₈ gives 16 mol of CO₂

0.54 mol of C₈H₁₈ gives $\frac{16 mol CO2 x 0.54 mol C8H18}{2 mol C8H18}$ mol of CO₂

= 4.32 mol of CO₂

Molar mass of CO₂ = 12 x 1 + 16 x 3 =60 g / mol

Mass of CO₂ = Molar mass of CO₂ x Number of moles of CO₂

= $\frac{60g x 4.32 mol}{1 mol}$

= 259.2 g

= $\frac{259.2}{1000}$

= 0.259 Kg

= 0.26 kg rounded off to 2 significant figures.

Thus if a tank of gasoline contains 80 liters and that its density is 0.77 kg/liter, 0.26 kg of CO₂ are produced for each tank of gasoline burned.

4 0

2 years ago