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Ray Of Light [21]
2 years ago
6

There are 15 technicians and 11 chemists working in a research laboratory. In how many ways could they form a 5-member safety co

mmittee if the committee a) may be chosen in any way? b) must have exactly one technician? c) must have exactly one chemist? d) must have exactly two chemists? e) may be all technicians or all chemists?
Chemistry
1 answer:
Fynjy0 [20]2 years ago
5 0

a)

26C5 -> 26 choices of 5 things

b)

15C1 × 11C4

c)

11C1 × 15C4

d)

11C2 × 15C2

e)

11C4

or

15C4

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Hydroxyapatite, Ca 10 ( PO 4 ) 6 ( OH ) 2 Ca10(PO4)6(OH)2 , has a solubility constant of Ksp = 2.34 × 10 − 59 2.34×10−59 , and d
Margarita [4]

Answer:

1.315x10⁻³M = [Ca²⁺]

Explanation:

Based in the reaction:

Ca₁₀(PO₄)₆(OH)₂(s) ⇄ 10Ca²⁺(aq) + 6PO₄³⁻(aq) + 2OH⁻(aq)

Solubility product, ksp, is defined as:

ksp = [Ca²⁺]¹⁰ [PO₄³⁻]⁶ [OH⁻]²

From 1 mole of hydroxyapatite are produced  10 moles of Ca²⁺ and 6 moles of PO₄³⁻. That means moles of PO₄³⁻ are:

6/10 Ca²⁺ = PO₄³⁻

Replacing in ksp formula:

ksp = [Ca²⁺]¹⁰ [0.6Ca²⁺]⁶ [OH⁻]²

As [OH⁻] is 2.50x10⁻⁶M and ksp is 2.34x10⁻⁵⁹:

2.34x10⁻⁵⁹ =  [Ca²⁺]¹⁰ [0.6Ca²⁺]⁶ [2.50x10⁻⁶]²

3.744x10⁻⁴⁸ = 0.046656[Ca²⁺]¹⁶

<em />

<em>1.315x10⁻³M = [Ca²⁺]</em>

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I hope it helps!

5 0
2 years ago
The amount of energy that must be absorbed or lost to raise or lower the temperature of 1 g of liquid water by 1°C _____.
MatroZZZ [7]

Answer:

c

Explanation:

1 calorie = 4.184J/g×°C

This also happens to be the specific heat capacity of water, which is the amount of energy it takes to raise the temperature of 1mL of water by 1°C

6 0
2 years ago
Recalling that a beaker of water is two dimensional, what is the three dimensional shape of the micelle
saul85 [17]
A micelle refers to an aggregate of a surfactant molecule, which a dispersed in a liquied colloid. In an aqueous liquid, a micelle is arranged in such a way that its hydrophillic head region will be in contact with the surrounding solvents while the hydrophobic tail region will be embedded in its center. 
The three dimensional shape of a micelle is A SPHERE. 
7 0
2 years ago
Ethylene (C2H4) is the starting material for the preparation of polyethylene. Although typically made during the processing of p
Solnce55 [7]

Answer:

1.17 grams

Explanation:

Let's consider the balanced equation for the combustion of ethylene.

C₂H₄(g) + 3 O₂(g) → 2 CO₂(g) + 2 H₂O(l)

We can establish the following relations:

  • 1411 kJ are released (-1411 kJ) when 1 mole of C₂H₄ burns.
  • The molar mass of C₂H₄ is 28.05 g/mol.

The grams of C₂H₄ burned to give 59.0 kJ of heat (q = -59.0 kJ) is:

-59.0kJ.\frac{1molC_{2}H_{4}}{-1411kJ} .\frac{28.05gC_{2}H_{4}}{1molC_{2}H_{4}} =1.17gC_{2}H_{4}

8 0
2 years ago
It takes 839./kJmol to break a carbon-carbon triple bond. Calculate the maximum wavelength of light for which a carbon-carbon tr
tresset_1 [31]

Answer:

The maximum wavelength of light for which a carbon-carbon triple bond could be broken by absorbing a single photon is 143 nm.

Explanation:

It takes 839 kJ/mol to break a carbon-carbon triple bond.

Energy required to break 1 mole of carbon-carbon triple bond = E = 839 kJ

E = 839 kJ/mol = 839,000 J/mol

Energy required to break 1 carbon-carbon triple bond = E'

E'=\frac{ 839,000 J/mol}{N_A}=\frac{839,000 J}{6.022\times 10^{23} mol^{-1}}=1.393\times 10^{-18} J

The energy require to single carbon-carbon triple bond will corresponds to wavelength which is required to break the bond.

E'=\frac{hc}{\lambda } (Using planks equation)

\lambda =\frac{6.626\times 10^{-34} Js\times 3\times 10^8 m/s}{1.393\times 10^{-18} J}

\lambda =1.427\times 10^{-7} m =142.7 nm = 143 nm

(1 m = 10^9 nm)

The maximum wavelength of light for which a carbon-carbon triple bond could be broken by absorbing a single photon is 143 nm.

6 0
2 years ago
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