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3 years ago

What is ph? And explain where it can be used

1 answer:

4 0

PH is a measure of hydrogen(colorless, odorless) concentration of solutions. Ph is in solutions for an example like spray to clean the kitchen counter or table.These things have color and are odorless after a while.

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Suppose the half-life is 9.0 s for a first order reaction and the reactant concentration is 0.0741 M 50.7 s after the reaction s

bazaltina [42]

Answer: The time taken by the reaction is 84.5 seconds

Explanation:

The equation used to calculate half life for first order kinetics:

$k=\frac{0.693}{t_{1/2}}$

where,

$t_{1/2}$ = half-life of the reaction = 9.0 s

k = rate constant = ?

Putting values in above equation, we get:

$k=\frac{0.693}{9}=0.077s^{-1}$

Rate law expression for first order kinetics is given by the equation:

$k=\frac{2.303}{t}\log\frac{[A_o]}{[A]}$ ......(1)

where,

k = rate constant = $0.077s^{-1}$

t = time taken for decay process = 50.7 sec

$[A_o]$ = initial amount of the reactant = ?

[A] = amount left after decay process = 0.0741 M

Putting values in equation 1, we get:

$0.077=\frac{2.303}{50.7}\log\frac{[A_o]}{0.0741}$

$[A_o]=3.67M$

Now, calculating the time taken by using equation 1:

$[A]=0.0055M$

$k=0.077s^{-1}$

$[A_o]=3.67M$

Putting values in equation 1, we get:

$0.077=\frac{2.303}{t}\log\frac{3.67}{0.0055}\\\\t=84.5s$

Hence, the time taken by the reaction is 84.5 seconds

6 0

4 years ago

What is the correct value using 3 significant figures for 14.8232 g/mol?

REY [17]

Answer:

14.8 g/mol

Explanation:

Starting on the left, count in 3 numbers (14.8), then round using the next number (0.02).

Because 2 is less than 5, the number stays the same and is not rounded up.

5 0

4 years ago

What are the first and second most abundant element in the universe?

UNO [17]

The answer to this is Hydrogen.

3 0

4 years ago

Metric conversions. Please help ASAP.

lesya692 [45]

Answer:

14. 13.2cg = 1.32dg

15. 3.8m = 0.0038km

16. 24.8L = 24800mL

17. 0.87kL = 870L

18. 26.01cm = 0.0002601km

19. 0.001hm = 10cm

Explanation:

14. 13.2/10 = 1.32

15. 38/1000 = 0.0038

16. 24.8(1000) = 24,800

17. 0.87(1000) = 870

18. 26.01/100000 = 0.0002601

19. 0.001hm(10000) = 10

An easy way to do these by yourself is to familiarize yourself with what each prefix means. Once you do this, you can multiply the value of the prefix when converting from a smaller unit of measurement to a larger one and divide the value of the prefix when converting from a large unit of measurement to a smaller one.

7 0

3 years ago

Number 8 pls step by stepA sample of gas has a mass of 20.00 g and occupies 44.8 L at STP. What is the molar mass of the gas?

LuckyWell [14K]

A sample of gas has a mass of 20.00 g and occupies 44.8 L at STP. What is the molar mass of the gas?

We know that 1 mol of an ideal gas at STP occupies 22.4 L. So we will use that relationship to find the number of moles of the gas that occupies 44.8 L.

number of moles = 44.8 L * 1 mol/(22.4 L) = 2.00 moles

number of moles = 2.00 moles

Another way of getting the same result is:

STP means that the pressure is 1 atm and the temperature is 273.15 K. And the volume of our sample is 44.8 L

P * V = n * R * T

n = P * V/(R * T)

n = 1 atm * 44.8 L / (0.082 atm*L/mol*K * 273.15 K)

n = 2.00 moles

So two moles of an ideal gas occupies 44.8 L at STP.

The mass of the sample is 20.00 g and we have 2 moles. So the molar mass is:

molar mass = (mass of sample)/(number of moles of the sample)

molar mass = 20.00 g/(2.00 moles)

molar mass = 10.0 g/mol

Another way of solving it:

Since the mass of two moles of our gas is 20.00 g, we can find the mass of 1 mol by solving this:

2.00 moles of gas ______ 20.00 g

1.00 mol of gas _____ x = ?

x = 1.00 mol * 20.00 g/2.00 moles = 10.0 g

So the mass of 1 mol is 10.0 g. Then the molar mass is 10.0 g/mol.

Answer: the molar mass of the gas is 10.0 g/mol

7 0

1 year ago