1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Vladimir [108]
3 years ago
6

A student carried out an acid-base titration by adding NaOH solution from a buret to an Erlenmeyer flask containing HCl solution

and using phenolphthalein as indicator. At the equivalence point, she observed a faint reddish-pink color. However, after a few minutes, the solution gradually turned colorless. What do you suppose happened?

Chemistry
1 answer:
Arada [10]3 years ago
3 0

Answer:

Shift in equilibrium position

Explanation:

The reddish-pink colour signalled the equivalence point. That is, pH=PKind. This was the point at which we have commonly the called the end point of the titration which has been carried out. As the solution was left to stand after this equivalence point was attained, the equilibrium position shifted again towards the acid side and the solution turned colourless once more. The equilibrium position indicated by the colour change depends on the H+ concentration of the solution.

You might be interested in
What mass in grams of MgSO4 is required to make 59.3 mL of 2.68 M<br> solution?
love history [14]

Answer:

Approximately 19.1\; \rm g.

Explanation:

<h3>Number of moles of formula units of magnesium sulfate required to make the solution</h3>

The unit of concentration in this question is "\rm M". That's equivalent to "\rm mol \cdot L^{-1}" (moles per liter.) In other words:

c(\mathrm{MgSO_4}) = 2.68\; \rm M = 2.68\; \rm mol \cdot L^{-1}.

However, the unit of the volume of this solution is in milliliters. Convert that unit to liters:

\displaystyle V = 59.3\; \rm mL = 59.3 \; \rm mL \times \frac{1\; \rm L}{1000\; \rm mL} = 0.0593\; \rm L.

Calculate the number of moles of \rm MgSO_4 formula units required to make this solution:

\begin{aligned}n(\rm MgSO_4) &= c \cdot V \\ &= 2.68 \; \rm mol \cdot L^{-1} \times 0.0593\; \rm L \approx 0.159\; \rm mol \end{aligned}.

<h3>Mass of magnesium sulfate in the solution</h3>

Look up the relative atomic mass data of \rm Mg, \rm S, and \rm O on a modern periodic table:

  • \rm Mg: 24.305.
  • \rm S: \rm 32.06.
  • \rm O: 15.999.

Calculate the formula mass of \rm MgSO_4 using these values:

M(\mathrm{MgSO_4}) = 24.305 + 32.06 + 4 \times 15.999 \approx 120.361\; \rm g \cdot mol^{-1}.

Using this formula mass, calculate the mass of that (approximately) 0.159\; \rm mol of \rm MgSO_4 formula units:

\begin{aligned}m(\mathrm{MgSO_4}) &= n \cdot M \\&\approx 0.159 \; \rm mol \times 120.361 \; \rm g \cdot mol^{-1} \approx 19.1\; \rm g\end{aligned}.

Therefore, the mass of \rm MgSO_4 required to make this solution would be approximately 19.1\; \rm g.

3 0
3 years ago
38.5 mol of P4O10 contains how many moles of P?
stellarik [79]

The subscripts tell the ratio of one element to another in a compound. In this case, there are 4 P atoms per 10 O atoms. This could also be interpreted as 4 mol P per 10 mol O. Therefore:

Mol P = (38.5 mol P4O10)/(4 mol P/ 1 mol P4O10) = 154 mol P 

6 0
4 years ago
Oh, no! You just spilled 85.00 mL of 1.500 M sulfuric acid on your lab bench and need to clean it up immediately! Right next to
vredina [299]

Explanation:

We will balance equation which describes the reaction between sulfuric acid and sodium bicarbonate: as follows.

   H_2SO_4(aq) + 2NaHCO_3(s) \rightarrow Na2SO_4(aq) + 2H_2O(l) + 2CO_2(g)

Next we will calculate how many moles of H_2SO_4 are present in 85.00 mL of 1.500 M sulfuric acid.

As,       Molarity = \frac{\text{moles of solute}}{\text{liters of solution&#10;}}

            1.500 M = \frac{n}{0.08500 L&#10;}

                    n = 0.1275 mol H_2SO_4

Now set up and solve a stoichiometric conversion from moles of H_2SO_4  to grams of NaHCO_3. As, the molar mass of NaHCO_3 is 84.01 g/mol.

 0.1275 mol H_2SO_4 \times (\frac{2 mol NaHCO_3}{1 mol H_2SO_4}) \times (\frac{84.01 g NaHCO_3}{1 mol NaHCO_3})

                 = 21.42 g NaHCO_3

So unfortunately, 15.00 grams of sodium bicarbonate will "not" be sufficient to completely neutralize the acid. You would need an additional 6.42 grams to complete the task.

4 0
3 years ago
For each solute identify the better solvent: water or carbon tetrachloride <br> Na2, I2, CCH2O, C6H6
Virty [35]
NH3 = water (it is actually a water soluble gas)
C6H14 = CCl4 (C6H14 won't mix with water at all)
Na2S = water (Na2S is a salt. Salts dissolve best in water)
Br2 = CCl4, but it will also dissolve in water.
3 0
3 years ago
Metals are cunductor of heat and electricity prove this statement​
Grace [21]

Answer:Metals are an excellent conductor of electricity and heat because the atoms in the metals form a matrix through which outer electrons can move freely. Instead of orbiting their respective atoms, they form a sea of electrons that surround the positive nuclei of the interacting metal ions.

Explanation:

7 0
3 years ago
Other questions:
  • A liquid has a volume of 0.0088 L. Convert this volume to cubic centimeters.
    13·1 answer
  • An element that has been broken down and released particles and energy is said to be ____.
    15·2 answers
  • How do a strong electrolyte, weak electrolyte, and non-electrolyte differ in the number of ions each produces when dissolved in
    8·1 answer
  • PLS HELP ASAP I REALLY NEED IT AND ILL MARK BRAINLIEST!
    12·1 answer
  • Identify which of the following are redox reactions. If a reaction is a redox reaction, name the element oxidized, the element r
    13·1 answer
  • According to the pattern of carbon and hydrogen atom, if a molecule has five carbon atom, how many hydrogen atom does it have
    13·1 answer
  • How current flows through a circuit <br>​
    13·1 answer
  • 1. Analyze Element A and Element B by describing how to test 3 physical or chemical properties of the elements.
    9·1 answer
  • 2. In which sentence is the term heat used correctly?
    10·2 answers
  • How much heat would be needed to change the temperature of 100g water from 10°C to 50°C?
    9·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!