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2 years ago

How many moles are in 15 grams of calcium

2 answers:

5 0

Atomic mass Ca = 40.0 u.m.a

1 mole Ca ------------- 40.0
? moles Ca ---------- 15 g

15 x 1 / 40 = 0.375 moles of Ca

chubhunter [2.5K]2 years ago

3 0

Approximately 0.374 moles

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Th e molar absorption coeffi cient of a substance dissolved in water is known to be 855 dm3 mol−1 cm−1 at 270 nm. To determine t

Olegator [25]

Answer : The percentage reduction in intensity is 79.80 %

Explanation :

Using Beer-Lambert's law :

$A=\epsilon \times C\times l$

$A=\log \frac{I_o}{I}$

$\log \frac{I_o}{I}=\epsilon \times C\times l$

where,

A = absorbance of solution

C = concentration of solution = $3.25mmol.dm^{3-}=3.25\times 10^{-3}mol.dm^{-3}$

l = path length = 2.5 mm = 0.25 cm

$I_o$ = incident light

$I$ = transmitted light

$\epsilon$ = molar absorptivity coefficient = $855dm^3mol^{-1}cm^{-1}$

Now put all the given values in the above formula, we get:

$\log \frac{I_o}{I}=(855dm^3mol^{-1}cm^{-1})\times (3.25\times 10^{-3}mol.dm^{-3})\times (0.25cm)$

$\log \frac{I_o}{I}=0.6947$

$\frac{I_o}{I}=10^{0.6947}=4.951$

If we consider $I_o$ = 100

then, $I=\frac{100}{4.951}=20.198$

Here 'I' intensity of transmitted light = 20.198

Thus, the intensity of absorbed light $I_A$ = 100 - 20.198 = 79.80

Now we have to calculate the percentage reduction in intensity.

$\% \text{reduction in intensity}=\frac{I_A}{I_o}\times 100$

$\% \text{reduction in intensity}=\frac{79.80}{100}\times 100=79.80\%$

Therefore, the percentage reduction in intensity is 79.80 %

3 0

3 years ago

How many Grams of NO is produced if 12g of O2 is combined with excess ammonia?

stich3 [128]

Answer:

Explanation:

moles O2 = mass / Mr = 12 / 2(16.0) = 0.375

ratio O2 : NO = 5:4

moles NO produced = 0.375 * 4/5 = 0.3

mass NO = Mr * mol = (14.0+16.0) * 0.3 = 9g

5 0

2 years ago

The volume of gas occupied 240.0ml when the pressure is 1.20 atm what volume at constant pressure.will the gas occupies when the

Marizza181 [45]

Answer:

334.89 ml

Explanation:

V2 = V1P1/P2

V2 = 240×1.2/0.86

V2 = 334.89 ml

7 0

2 years ago

The number of neutrons in the nucleus of an atom can be determined by

Masteriza [31]

Option no. 2 subtracting the atomic number from the mass number

Example: Zn - 65 atomic weight or mass/mass number
30 atomic number

65-30 = 35 number of neutrons

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2 years ago

#1. Which of the following is a reasonable ground-state electron configuration? A.-1s21p62s22p63s2/ B. -1s22s22p63s23p64s24d8/ C

Sladkaya [172]

A ground state electron configuration follows the Aufbau Principle that states that electrons should be filled up in orbitals in increasing energy. In the given sequences, the right configuration is <span>1s2 2s2 2p6 3s2 3p6 4s2 3d8. The choice that conforms to this sequence is D. In 2) the possible confirmation that follows Aufbau's principle is D. </span>

6 0

2 years ago

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