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2 years ago

Explain how the cell membrane controls the movement of materials into and out of the cell ?

1 answer:

5 0

It's called simple diffusion, the small molecules without charges such as oxygen and carbon dioxide can flow through a plasma membrane without assistance and without expending energy. Other substances such as proteins, glucose and charged particles called ions cannot pass through the selectively permeable membrane.

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Aluminum boils at 2467°C. Aluminum’s boiling point in Kelvin is 2194.<br> T or F

dusya [7]

That is false because aluminum melts at 2,470C

7 0

2 years ago

Why do you think plant cells need a cell wall as well as a cell membrane?

Sergio039 [100]

Answer:

to protect it from harm

Explanation:

3 0

3 years ago

Pls help me i dont know this

r-ruslan [8.4K]

Answer:

1. 12.6 moles

2. 8.95 moles

3. 2A + 5B → 3C

4. 48 moles

Explanation:

1. 2Fe + 3Cl₂ → 2FeCl₃

We assume the chlorine in excess. Ratio is 2:2

2 moles of Fe, can produce 2 moles of chloride

12.6 moles of Fe will produce 12.6 moles of chloride.

2. 2Fe + 3Cl₂ → 2FeCl₃

For the same reaction, first of all we need to convert the mass to moles:

500 g . 1mol / 55.85 g = 8.95 mol

As ratio is 2:2, the moles we have are the same, that the produced

4. The reaction for the combustion is:

2C₂H₆ (g) + 7O₂ (g) → 4CO₂ (g) + 6H₂O (l)

We assume the oxygen in excess.

Ratio is 2:6, so 2 mol of ethane produce 6 moles of water

Therefore 16 moles of ethane may produce (16 .6) / 2 = 48 moles

3 0

3 years ago

The addition of 0.275 L of 1.62 M KCl to a solution containing Ag+ and Pb2+ ions is just enough to precipitate all of the ions

musickatia [10]

Answer:

The mass of PbCl₂ is 45.88 grams and the mass of AgCl is 16.48 grams.

Explanation:

As mentioned in the given question, the addition of 0.275 L of 1.62 M KCl is done in a solution that comprise Ag⁺ and Pb²⁺ ions so that all the ions get precipitated. Therefore, the moles of KCl present is,

Moles of KCl = 0.275 L × 1.62 M = 0.445 moles

Now the reaction will be,

Ag⁺ + Pb²⁺ + KCl ⇒ AgCl + PbCl₂ + 3K⁺

Now let us assume that the formation of x moles of AgCl and y moles of PbCl₂ is taking place.

Therefore, mass of AgCl will be x × molecular mass, which will be equal to x × 143.32 grams = 143.32 x grams

Now the mass of PbCl2 formed will be,

y × molecular mass = y × 278.1 grams = 278.1 y grams

Now the total precipitate will be,

62.37 grams = 143.32 x + 278.1 y -----------(i)

Now as AgCl and PbCl₂ requires 1:2 ratio of KCl, this shows that x moles of AgCl will require x moles of KCl and y mol of PbCl₂ will require 2*y moles of PbCl₂. Therefore,

x + 2y = total mass of KCl

x + 2y = 0.445 moles ------ (ii)

On solving equation (i) and (ii) we get,

x as 0.115 and y as 0.165

Now the mass of AgCl will be,

143.32 × 0.115 = 16.48 grams

The mass of PbCl₂ will be,

278.1 × 0.165 = 45.88 grams.

3 0

3 years ago

Liquid helium boils at –268.93 °C. What is the boiling point of helium on the Kelvin temperature scale?

BARSIC [14]

In order to change celcius to kelvin always add 73 to it leaving you with -195.93

4 0

2 years ago

Read 2 more answers