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monitta
3 years ago
5

When does phenolphthalein turn pink?

Chemistry
2 answers:
lesya692 [45]3 years ago
5 0
A.) <span>Phenolphthalein is colorless in an acid, but it turns bright pink in the presence of a base.

Hope I helped you!!</span>
Svetach [21]3 years ago
3 0

Answer is: a) in the presence of a base.

Phenolphthalein is colorless in acidic solutions and pink in basic solutions.

Acid-base indicators are usually weak acids or bases and they are chemical detectors for hydrogen or hydronium cations.

Example for acid-base indicator is phenolphthalein (molecular formula C₂₀H₁₄O₄).

When solution turns phenolphthalein pink, it means it is basic (pH>7).

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During laparoscopic surgery , carbon dioxide gas is used to expand the abdomen to help create a larger working space. If 4.80 L
Studentka2010 [4]

Answer:

5.37 L

Explanation:

To solve this problem we need to use the PV=nRT equation.

First we <u>calculate the amount of CO₂</u>, using the initial given conditions for P, V and T:

  • P = 785 mmHg ⇒ 785/760 = 1.03 atm
  • V = 4.80 L
  • T = 18 °C ⇒ 18 + 273.16 = 291.16 K

1.03 atm * 4.80 L = n * 0.082 atm·L·mol⁻¹·K⁻¹ * 291.16 K

We <u>solve for n</u>:

  • n = 0.207 mol

Then we use that value of n for another PV=nRT equation, where T=37 °C (310.16K) and P = 745 mmHg (0.98 atm).

  • 0.98 atm * V = 0.207 mol * 0.082 atm·L·mol⁻¹·K⁻¹ * 310.16 K

And we <u>solve for V</u>:

  • V = 5.37 L
7 0
3 years ago
How many Joules are there in 55 nutritional calories?
Sidana [21]

Answer:

230.12

Explanation:

8 0
3 years ago
How many grams of O2(g) are needed to completely burn 46.0 g C3H8(g)?
Veronika [31]

Answer:

167,3 grams of O2 (g)

Explanation:

According to the following balanced equation:

C3H8 + 5 02 ---> 3 CO2 + 4 H20

We calculate the mass of the moles:

5 mol O2 = 16grams/mol x2x 5= 160 grams/mol

1 mol C3H8= 3 x12 grams/mol + 8 x 1 gram/mol= 44 grams/mol

If 44 grams C3H8 react with--------- 160 grams O2

46 gramsC3H8 react with    --------X = (46x160)/44 =167, 3 grams O2

8 0
4 years ago
During a chemical reaction, an iron atom became the ion Fe2+. What happened to the iron atom?
kirill115 [55]

Explanation:

Iron atom is been oxidised as it losses 2 electron to form 2 + ion.

4 0
3 years ago
A lead–tin alloy of composition 30 wt% Sn–70 wt% Pb is slowly heated from a temperature of 150°C (300°F).(a) At what temperature
Novay_Z [31]

Answer:

a) 231.9 °C

b) 100% Sn

c) 327.5 °C

d) 100% Pb

Explanation:

This is a mixture of two solids with different fusion point:

Tf_{Pb}=327.5 C

Tf_{Sn}=231.9 C

<u>Given that Sn has a lower fusion temperature it will start to melt first at that temperature. </u>

So the first liquid phase forms at 231.9 °C and because Pb starts melting at a higher temperature, that phase's composition will be 100% Sn.

The mixture will be completely melted when you are a the higher melting temperature of all components (in this case Pb), so it will all in liquid phase at 327.5 °C.

At that temperature all Sn was already in liquid state and, therefore, the last solid's composition will be 100% Pb.

3 0
4 years ago
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