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defon
3 years ago
12

How do we know that a chemical reaction occured

Chemistry
1 answer:
gregori [183]3 years ago
8 0

Answer: signs of a chemical change are a change in color and the formation of bubbles. The five conditions of chemical change: color change, formation of a precipitate, formation of a gas, odor change, temperature change.

Explanation:

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The iodine "clock reaction" involves the following sequence of reactions occurring in a reaction mixture in a single beaker. 1.
Mars2501 [29]

C: 0.012 mol.

<h3>Explanation</h3>

Start with 0.0020 moles of iodate ions {\text{IO}_{3}}^{-}.

How many moles of iodine \text{I}_2 will be produced?

{\text{IO}_{3}}^{-} converts to \text{I}_2 in the first reaction. The coefficient in front of \text{I}_2 is three times the coefficient in front of {\text{IO}_{3}}^{-}. In other words, each mole of {\text{IO}_{3}}^{-} will produce three moles of \text{I}_2. 0.0020 moles of {\text{IO}_{3}}^{-} will convert to 0.0060 moles of \text{I}_2.

How many moles of thiosulfate ions {\text{S}_2\text{O}_3}^{2-} are required?

\text{I}_2 reacts with {\text{S}_2\text{O}_3}^{2-} in the second reaction. The coefficient in front of \text{I}_2 is twice the coefficient in front of {\text{S}_2\text{O}_3}^{2-}. How many moles of {\text{S}_2\text{O}_3}^{2-} does each mole of \text{I}_2 consume? Two. 0.0060 moles of \text{I}_2 will be produced. As a result, 2 \times 0.0060 = 0.0120 moles of {\text{S}_2\text{O}_3}^{2-} will be needed.

6 0
3 years ago
Calculate the density of helium if a balloon with a capacity of 5.00 L holds 0.890 g.
liubo4ka [24]

Answer:

Explanation:

Density is m/V. Also, 1 liter = 1000 cm^3. So, we get 0.890/(5*1000) = 1.78*10^{-4} g/cm^3. You can convert this to kg/m^3 as well by multiplying it by 10. Depends which one you want.

5 0
3 years ago
The state of the atmosphere at a given time and place is called
s344n2d4d5 [400]

Answer:a

Explanation:

6 0
3 years ago
Read 2 more answers
Calcium hydroxide is a strong base but is not very soluble ( Ksp = 5.02 X 10-6 ). What is the pH of a saturated solution of Ca(O
Misha Larkins [42]

Answer : The pH of a saturated solution is, 12.33

Explanation : Given,

K_{sp} = 5.02\times 10^{-6}

First we have to calculate the solubility of OH^- ion.

The balanced equilibrium reaction will be:

Ca(OH)_2\rightleftharpoons Ca^{2+}+2OH^-

Let the solubility will be, 's'.

The concentration of Ca^{2+} ion = s

The concentration of OH^- ion = 2s

The expression for solubility constant for this reaction will be,

K_{sp}=[Ca^{2+}][OH^-]^2

Let the solubility will be, 's'

K_{sp}=(s)\times (2s)^2

K_{sp}=(4s)^3

Now put the value of K_[sp} in this expression, we get the solubility.

5.02\times 10^{-6}=(4s)^3

s=1.079\times 10^{-2}M

The concentration of Ca^{2+} ion = s = 1.079\times 10^{-2}M

The concentration of OH^- ion = 2s = 2\times (1.079\times 10^{-2}M)=2.158\times 10^{-2}M

First we have to calculate the pOH.

pOH=-\log [OH^-]

pOH=-\log (2.158\times 10^{-2})

pOH=1.67

Now we have to calculate the pH.

pH+pOH=14\\\\pH=14-pOH\\\\pH=14-1.67=12.33

Therefore, the pH of a saturated solution is, 12.33

7 0
3 years ago
What is the wavelength of a 2500 kg truck traveling at a rate of 75km/h?
Pepsi [2]

m = mass of the truck traveling = 2500 kg

v = speed of the truck traveling = 75 km/h = 75 (km/h) (1000 m/ 1 km) (1 h /3600 sec) = 20.83 m/s

h = plank's constant = 6.63 x 10⁻³⁴

λ = wavelength of truck = ?

according to de broglie's principle, wavelength of truck is given as

λ = h/(mv)

inserting the values in the above equation

λ = (6.63 x 10⁻³⁴)/((2500) (20.83))

λ = 1.3 x 10⁻³⁸ m

5 0
3 years ago
Read 2 more answers
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