What percentage of carpet is calcium carbonates?

Which best describe the isovolumetric contraction phase of the cardiac cycle?

cluponka [151]

The name isovolumetric indicates that there is no change in volume that takes place and this only occurs when all of the valves within the heart are shut.

5 0

3 years ago

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What is the pressure in millimeters of mercury of 0.0130 molmol of helium gas with a volume of 210. mLmL at 55 ∘C∘C? (Hint: You

juin [17]

Answer : The pressure of the helium gas is, 1269.2 mmHg

Explanation :

To calculate the pressure of the gas we are using ideal gas equation:

$PV=nRT$

where,

P = Pressure of $He$ gas = ?

V = Volume of $He$ gas = 210. mL = 0.210 L (1 L = 1000 mL)

n = number of moles $He$ = 0.0130 mole

R = Gas constant = $0.0821L.atm/mol.K$

T = Temperature of $He$ gas = $55^oC=273+55=328K$

Putting values in above equation, we get:

$P\times 0.210L=0.0130mole\times (0.0821L.atm/mol.K)\times 328K$

$P=1.67atm=1269.2mmHg$

Conversion used : (1 atm = 760 mmHg)

Thus, the pressure of the helium gas is, 1269.2 mmHg

4 0

3 years ago

Complete combustion of 3.20g of a hydrocarbon produced 9.69g of CO2 and 4.96g of H2O. What is the empirical formula for the hydr

vlabodo [156]

Let empirical formula for hydrocarbon is CxHy

it will undergo combustion as

CxHy + (x + y/4) O2 ---> xCO2 + (y/2 )H2O

Given that mass of CO2 produced = 9.69 g

So moles of CO2 produced = 9.69 / 44 = 0.22 moles

So moles of carbon present = 0.22 moles

mass of H2O produced = 4.96 g

Moles of H2O produced = mass / molar mass = 4.96 / 18 = 0.28 moles

So moles of H present = 2 X 0.28 = 0.56 moles

Let us divided the moles of each with lowest value of moles

Moles of Carbon = 0.22 / 0.22 = 1 moles

moles of H = 0.56 / 0.22 = 2.55

Multiplying with two to get whole number

the ratio of carbon and hydrogen will be : C:H = 2:5

empirical formula : C2H5

4 0

3 years ago

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Ka/KbMIXED PRACTICE108.Calculate the [H3O+(aq)], the pH, and the % reaction for a 0.50 mol/L HCN solution. ([H3O+(aq)] = 1.8 x 1

NeTakaya

Answer:

a) [H₃O⁺] = 1.8x10⁻⁵ M

b) pH = 4.75

c) % rxn = 3.5x10⁻³ %

Explanation:

a) The dissociation reaction of HCN is:

HCN(aq) + H₂O(l) ⇄ H₃O⁺(aq) + CN⁻(aq)

0.5 M - x x x

The dissociation constant from the above reactions is given by:

$Ka = \frac{[H_{3}O^{+}][CN^{-}]}{[HCN]} = 6.17 \cdot 10^{-10}$

$6.17 \cdot 10^{-10} = \frac{x*x}{(0.5 - x)}$

$6.17 \cdot 10^{-10}*(0.5 - x) - x^{2} = 0$

By solving the above quadratic equation we have:

x = 1.75x10⁻⁵ M = 1.8x10⁻⁵ M = [H₃O⁺] = [CN⁻]

Hence, the [H₃O⁺] is 1.8x10⁻⁵ M.

b) The pH is equal to:

$pH = -log[H_{3}O^{+}] = -log(1.75 \cdot 10^{-5} M) = 4.75$

Then, the pH of the HCN solution is 4.75.

c) The % reaction is the % ionization:

$\% = \frac{x}{[HCN]} \times 100$

$\% = \frac{1.75 \cdot 10^{-5} M}{0.5 M} \times 100$

$\% = 3.5 \cdot 10^{-3} \%$

Therefore, the % reaction or % ionization is 3.5x10⁻³ %.

I hope it helps you!

6 0

2 years ago

You discover a bottle of aqueous sodium chloride of unknown molarity. However, the bottle says that there are 0.75 moles of NaCl

lara31 [8.8K]

To calculate the molarity you only need to know the number of moles in the solution and the volume of that solution. This exercise gives both and with that you divide moles by volume(usually in liters).

500 ml equals 0,5 L
molarity= number of moles/ volume
molarity=0,75 x 0,5
= 0,375 mol/L

6 0

3 years ago