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3 years ago

What is the ph of a solution with [h3o+] = 1 × 10-9 m?

1 answer:

7 0

PH scale is used to determine how acidic, basic or neutral a solution is
pH can be calculated using the H₃O⁺
ph can be calculated as follows
pH = - log[ H₃O⁺]
[H₃O⁺] = 1 x 10⁻⁹
pH = - log [1 x 10⁻⁹]
pH = 9
pH of solution is 9

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A sample of paper from an ancient scroll was found to contain 39.5% 14C content as compared to a present-day sample. The t1/2 fo

nirvana33 [79]

Answer

7665 years

Procedure

Let N₀ be the amount of carbon-14 present in a living organism. According to the radioactive decay law, the number of carbon-14 atoms, N, left in a dead tissue sample after a certain time, t, is given by the exponential equation:

N = N₀e^(-λt)

where λ is the decay constant which is related to half-life (T1/2) by the equation:

$\lambda=\frac{ln(2)}{t_{\frac{1}{2}}}$

Here, ln(2) is the natural logarithm of 2.

The percent of carbon-14 remaining after time t is given by N/N₀.

Using the first equation, we can determine λt.

The half-life of carbon-14 is 5,720 years, thus, we can calculate λ using the second equation, and then find t.

$\lambda=\frac{ln(2)}{5720}=1.211\times10^{-4}$

Solving the second equation for t, and using the λ we have just calculated we will have

t= 7665 years

3 0

1 year ago

Calculate the molarity of a solution that contains 3.11 mol of NaNO3 dissolved in 2.50 L. Enter your answer in the provided box.

rusak2 [61]

Answer:

Molarity of a solution that contains 3.11 mol of NaNO3 is 1,24 M

Explanation:

We understand molarity as the number of moles of solute that are contained in 1 L of solution, then if in a solution of 2.50 L we have 3.11 moles, it remains to calculate how many moles do we have in 1 liter.

2,50 L .......... 3,11 moles

1 L .................. x

X = ( 1 L x 3,11 moles) / 2,50 L = 1,24

8 0

3 years ago

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Verizon [17]

Answer:

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Explanation:

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3 years ago

How many moles of N20 gas would have a volume of 3.8 L at 460 mmHg and 77°C?

Citrus2011 [14]

We are given:

Volume of gas = 3.8 L

Pressure = 460 mmHg

Temperature = 77°c = (77+273)K = 350K

Converting the pressure to atm:

Pressure(in atm) = Pressure(in mmHg) / 760

Pressure = 460/760 = 0.6 atm

Finding the number of moles:

using the ideal gas equation:

PV = nRT [where R is the universal gas constant]

replacing the given values in this equation

(0.6)(3.8) = n(0.082)(350)

n = (0.6*3.8)/(0.082*350)

n = 0.08 moles

7 0

3 years ago

100. mg of an unknown protein are dissolved in enough solvent to make 5.00mL of solution. The osmotic pressure of this solution

PolarNik [594]

Answer: The molar mass of the unknown protein is 6387.9 g/mol

Explanation:

To calculate the concentration of solute, we use the equation for osmotic pressure, which is:

$\pi=iMRT$

or,

$\pi=i\times \frac{\text{Mass of solute}\times 1000}{\text{Molar mass of solute}\times \text{Volume of solution (in mL)}}\times RT$

where,

$\pi$ = osmotic pressure of the solution = 0.0766 atm

i = Van't hoff factor = 1 (for non-electrolytes)

Mass of protein = 100. mg = 0.100 g (Conversion factor: 1 g = 1000 mg)

Molar mass of protein = ?

Volume of solution = 5.00 mL

R = Gas constant = $0.0821\text{ L atm }mol^{-1}K^{-1}$

T = temperature of the solution = $25^oC=[25+273]K=298K$

Putting values in above equation, we get:

$0.0766atm=1\times \frac{0.100\times 1000}{\text{Molar mass of protein}\times 5}\times 0.0821\text{ L. atm }mol^{-1}K^{-1}\times 298K\\\\\pi=\frac{1\times 0.100\times 1000\times 0.0821\times 298}{0.0766\times 5}=6387.9g/mol$

Hence, the molar mass of the unknown protein is 6387.9 g/mol

5 0

4 years ago