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3 years ago

10

indicators are chemicals that change colour in presence of an acid or an alkali. Universal indicators and pH meters are used to

measure pH. Desccribe how you would use a universal indicator to find the pH of sodium hydroxide. What colour change would you observe

1 answer:

Troyanec [42]3 years ago

7 0

Answer:

Purple. Sodium Hydroxide is an Alkali/base. Bases and Alkalis

have a pH greater than 7, and turn blue-purple in universal

indicator.

Explanation:

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What is the total probability of finding a particle in a one-dimensional box in level n = 4 between x = 0 and x = L/8?

Lubov Fominskaja [6]

Answer:

P = 1/8

Explanation:

The wave function of a particle in a one-dimensional box is given by:

$\psi = \sqrt \frac{2}{L} sin(\frac{n \pi x}{L})$

Hence, the probability of finding the particle in the one-dimensional box is:

$P = \int_{x_{1}}^{x_{2}} \psi^{2} dx$

$P = \int_{x_{1}}^{x_{2}} (\sqrt \frac{2}{L} sin(\frac{n \pi x}{L}))^{2} dx$

$P = \frac{2}{L} \int_{x_{1}}^{x_{2}} (sin^{2}(\frac{n \pi x}{L}) dx$

Evaluating the above integral from x₁ = 0 to x₂ = L/8 and solving it, we have:

$P = \frac{2}{L} [\frac{L}{16} (1 - 4\frac{sin(\frac{n \pi}{4})}{n \pi})]$

$P = \frac{1}{8} (1 - 4\frac{sin(\frac{n \pi}{4})}{n \pi})$

Solving for n=4:

$P = \frac{1}{8} (1 - 4\frac{sin(\frac{4 \pi}{4})}{4 \pi})$

$P = \frac{1}{8} (1 - \frac{sin (\pi)}{\pi})$

$P = \frac{1}{8}$

I hope it helps you!

7 0

3 years ago

A first-order decomposition reaction has a rate constant of 0.00440 yr−1. How long does it take for [reactant] to reach 12.5% of

mina [271]

Answer:

473 year

Explanation:

Using integrated rate law for first order kinetics as:

$[A_t]=[A_0]e^{-kt}$

Where,

$[A_t]$ is the concentration at time t

$[A_0]$ is the initial concentration

Given:

To reach 12.5% of reactant means that 0.125 of $[A_0]$ is decomposed. So,

$\frac {[A_t]}{[A_0]}$ = 0.125

t = ?

$\frac {[A_t]}{[A_0]}=e^{-k\times t}$

$0.125=e^{-0.00440\times t}$

t = 473 year

8 0

3 years ago

Which compound dissolves in water to form an aqueous solution that can conduct an electric current?

drek231 [11]

The answer is (3) CH3COOH. CH3COOH is a acid. It can ionized in water. So the solution can conduct an electric current. And the other three can not be ionized in water.

4 0

3 years ago

Lead can be prepared from galena [lead(II) sulfide] by first roasting the galena in oxygen gas to form lead(II) oxide and sulfur

Vesna [10]

Answer:

a) Step 1:

$2PbS(g)+3O_2(g)\overset{roasting}\rightarrow 2PbO(s)+2SO_2(g)$

Step 2:

$2PbO(s)+PbS(s)\overset{\Delta }\rightarrow 3Pb(l)+SO_2(g)$

b) The overall balanced reaction for given process is ;

$3PbS(s)+3O_2(g)\rightarrow 3Pb(l)+3SO_2(g)$

Explanation:

a)

Galena = $PbS$

Lead(II) oxide = $PbO$

Sulfur dioxide = $SO_2$

Step 1:

Roasting the galena in oxygen gas to form lead(II) oxide and sulfur dioxide.

Balanced equation of step 1:

$2PbS(g)+3O_2(g)\overset{roasting}\rightarrow 2PbO(s)+2SO_2(g)$ ..[1]

Step 2:

Heating the metal oxide with more galena forms the molten metal and more sulfur dioxide.

Balanced equation of step 2:

$2PbO(s)+PbS(s)\overset{\Delta }\rightarrow 3Pb(l)+SO_2(g)$ ..[2]

b)

For over all reaction add [1] and [2]. The overall balanced reaction for given process is ;

$3PbS(s)+3O_2(g)\rightarrow 3Pb(l)+3SO_2(g)$

5 0

3 years ago

Read 2 more answers

What's the most unreactive metal?

Simora [160]

Answer:

gold and platinum

Explanation:

Very unreactive metals, such as gold and platinum, are found in the Earth's crust as pure metals. These are called native metals.

6 0

2 years ago