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3 years ago

Which most likely indicates a chemical change has occurred?

1 answer:

8 0

Chemical change can be determined when a substance change it's state of composition and is irreversible. Five evidences that chemical change has occured are, color change, formation of a precipitate, formation of gas, odor change, temperature change. Examples of chemical change are, combustion reactions, rusting iron, precipitate of AgCl.

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In a certain industrial process involving a heterogeneous catalyst, the volume of the catalyst (in the shape of a sphere) is 10.

olga nikolaevna [1]

Answer:

a. The second run will be faster.

d. The second run has twice the surface area.

Explanation:

The rate of a reaction is proportional to the surface area of a catalyst. Given the volume (V) of a sphere, we can find its surface area (A) using the following expression.

$A=\pi ^{1/3} (6V)^{2/3}$

The area of the 10.0 cm³-sphere is:

$A=\pi ^{1/3} (6.10.0)^{2/3}=22.4cm^{2}$

The area of each 1.25 cm³-sphere is:

$A=\pi ^{1/3} (6. 1.25)^{2/3}=5.61cm^{2}$

The total area of the 8 1.25cm³-spheres is 8 × 5.61 cm² = 44.9 cm²

The ratio of 8 1.25cm³-sphere to 10.0 cm³-sphere is 44.9 cm²/22.4 cm² = 2.00

Since the surface area is doubled, the second run will be faster.

6 0

3 years ago

QUESTION 5

amid [387]

Answer:

m+/+

commen+/0

para +/-

compe-/-

Explanation:

8 0

3 years ago

50.0 mL of 0.200 M HNO2 is titrated to its equivalence point with 1.00 M NaOH. What is the pH at the equivalence point?

yKpoI14uk [10]

Answer:

8.279

Explanation:

The pH can be determined by hydrolysis of a conjugate base of weak acid at the equivalence point.

At the equivalence point, we have

$n_{NaOH}=n_{HNO_2}$

= 25.00 x 0.200

= 5.00 m-mol

= 0.005 mol

Volume of the base that is added to reach the equivalence point is

$\frac{0.005}{1.00} \times 1000= 5.00 \ mL$

Number of moles of $NO^-_{2}=n_{HNO_2}$

= 0.005 mol

Volume at the equivalence point is 25 + 5 = 30.00 mL

Therefore, concentration of $NO^-_{2}= \frac{5}{30}$

= 0.167 M

Now the ICE table :

$NO^-_2 + H_2O \rightarrow HNO_3 + OH^-$

I (M) 0.167 0 0

C (M) -x +x +x

E (M) 0.167-x x x

Now, the value of the base dissociation constant is ,

$K_w=K_a \times K_b$ $(K_w \text{ is the ionic product of water })$

$K_b =\frac{K_w}{K_a}$

$K_b =\frac{1 \times 10^{-14}}{4.6 \times 10^{-4}}$

= $2.174 \times 10^{-11}$

Base ionization constant, $K_b = \frac{\left[HNO_2\right] \left[OH^- \right]}{\left[NO^-_2 \right]}$

$2.174 \times 10^{-11}=\frac{x^2}{0.167 -x}$

$x= 1.9054 \times 10^{-6}$

So, $[OH^-]=1.9054 \times 10^{-6 } \ M$

pOH =- $\log[OH^-]$

= $- \log(1.9054 \times 10^{-6} \ M)$

=5.72

Now, since pH + pOH = 14

pH = 14.00 - 5.72

= 8.279

Therefore the ph is 8.279 at the end of the titration.

8 0

3 years ago

How do calculate the molar mass

Katena32 [7]

Answer:

To calculate the molar mass of a compound with multiple atoms, sum all the atomic mass of the constituent atoms molar mass can also be calculated by multiplying the atomic mass in amu by the molar mass constant (1 g/mol).

7 0

3 years ago

Weather is influenced by global patterns of atmospheric movement. Winds and

Sholpan [36]

Winds and ocean currents are evidence for the process of regulating and stabilizing the climate patterns.

<h3>What are winds and ocean currents?</h3>

Ocean current is the flow or movement of water in a direction by gravity, wind, and difference in density of the water.

Wind currents pull water and create ocean currents. The current flow to westwards, which is called Coriolis effect.

Thus, Winds and ocean currents are evidence for the process of regulating and stabilizing the climate patterns.

Learn more about ocean currents

brainly.com/question/21654036

#SPJ1

6 0

2 years ago