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3 years ago

NEED HELP 14 points!!!

Chemistry

1 answer:

evablogger [386]3 years ago

5 0

Answer: 45 moles H2O

Explanation: To solve for the moles of H2O in the reaction we will use the mole ratio of O2 and H2O based from the chemical equation which is 1 : 2

22.5 moles O2 x 2 moles H2O / 1 mole O2

= 45 moles H2O

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A solution was made by dissolving 5.10 mg of hemoglobin in water to give a final volume of 1.00 ml. the osmotic pressure of this

Assoli18 [71]

The molecular weight of hemoglobin can be calculated using osmotic pressure

Osmotic pressure is a colligative property and it depends on molarity as

πV = nRT

where

π = osmotic pressure

V = volume = 1mL = 0.001 L

n = moles

R = gas constant = 0.0821 L atm / mol K

T = temperature = 25°C = 25 + 273 K = 298 K

Putting values we will get value of moles

$moles=\frac{\pi V}{RT}=\frac{0.00195X0.001}{0.0821X298}mol$

we know that

$moles=\frac{mass}{molarmass}$

Therefore

$molarmass=\frac{mass}{moles}=\frac{5.10X10^{-3}g}{7.97X10^{-8}}=6.399X10^{4}g$

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2 years ago

The half-life of radium-226 is 1590 years. (a) A sample of radium-226 has a mass of 50 mg. Find a formula for the mass of the sa

Maksim231197 [3]

Answer:

Explanation:

a )

m = m₀ $e^{-\lambda t$

m is mass after time t . original mass is m₀ , λ is disintegration constant

λ = .693 / half life

= .693 / 1590

= .0004358

m = m₀ $e^{- 0.0004358 t}$

b )

m = 50 x $e^{-.0004358\times 500}$

= 40.21 mg .

c )

40 = 50 $e^{-.0004358t$

.8 = $e^{-.0004358t$

$e^{.0004358t$ = 1.25

.0004358 t = .22314

t = 512 years .

4 0

2 years ago

How many electrons occupy a filled 7s sublevel

Natali5045456 [20]

Answer:f has 14 electrons in 7 sublevel orbitals,d has 10 electrons in 5 sublevel orbitals,p has 6 electrons in 3 sublevel orbitals,s has 2 electrons in 1 sublevel orbital.

Explanation:

3 0

3 years ago

Read 2 more answers

What are the spectator ions in the equation below? Select all that apply.

Licemer1 [7]

Answer:

H+ and NO3- ions

Explanation:

The Pb²+ ions react with the SO4²‐ ions to form a solid precipitate, i.e. they bond together and undergo a phase change;

On the contrary, the H+ and NO3- ions are aqueous ions before the reaction and the same after the reaction, i.e. they don't change;

Hence, the H+ and NO3- ions are spectator ions

The way to do this type of question is to consider what changes and what doesn't, look at phase changes and oxidation state changes

7 0

2 years ago

As an athlete exercises, sweat is produced and evaporated to help maintain a proper body temperature. On average, an athlete los

dmitriy555 [2]

<u>Answer:</u> For the given amount of sweat lost, the amount of energy required will be 692,899 Joules.

<u>Explanation:</u>

We are given:

Heat of vaporization for water = 2257 J/g

Amount of sweat lost = 307 grams

Applying unitary method:

For 1 g of sweat lost, the energy required is 2257 Joules

So, for 307 grams of sweat lost, the energy required will be = $\frac{2257J}{1g}\times 307g=692,899J$

Hence, for the given amount of sweat lost, the amount of energy required will be 692,899 Joules.

7 0

2 years ago