Answer:
109.0
Explanation:
When adding or subtracting values, you must round your answer to the same "place" as the measurement with its last significant figure <em>furthest to the left</em>.
That is, you round off to the same number of decimal places as the measurement with the <em>fewest decimal places</em>.
43.<u>0
</u>
50.<u>0</u>
<u>+16.0
</u>
109.<u>0</u>
In each measurement, the “0” is the significant figure furthest to the left, so you round off the number to the “tenths" place. That's the last column that the measurements share.
109.0 → 109.0 (rounded to the “tenths” place)
In other words, you do not round off, and the sum has four significant figures.
Answer:
3 mol
Explanation:
Given data:
Volume of ethane = 15.0 L
Temperature = 30°C
Pressure = 5.0 atm
Number of moles of ethane = ?
Solution:
PV = nRT
P= Pressure
V = volume
n = number of moles
R = general gas constant = 0.0821 atm.L/ mol.K
T = temperature in kelvin
Now we will convert the temperature.
30+273 = 303 K
5.0 atm × 15.0 L = n×0.0821 atm.L/ mol.K × 303 K
75 atm.L = n× 24.87 atm.L/ mol
n = 75 atm.L / 24.87 atm.L/ mol
n = 3 mol
For the reaction 2 K + F2 --> 2 KF,
consider K atomic wt. = 39
23.5 g of K = 0.603 moles, hence following the molar ratio of the balanced equation, 0.603 moles of potassium will use 0.3015 moles of F2. (number of moles, n = 0.3015)
Now, following the ideal gas equation, PV = nRT
P = 0.98 atm
V = unknown
n = 0.3015 moles
R = 82.057 cm^3 atm K^-1mole^-1 (unit of R chosen to match the units of other parameters; see the reference below)
T = 298 K
Solving for V,
V = (nRT)/P = (0.3015 mol * 82.057 cm^3 atm K^-1 mol^-1 * 298 K)/(0.98 atm)
solve it to get 7517.6 cm^3 as the volume of F2 = 7.5176 liters of F2 gas is needed.
2. Use the formula: volume1 * concentration 1 = volume 2 * concentration 2
where, volume 1 and concentration 1 are for solution 1 and volume 2 and solution 2 for solution 2.
Solution 1 = 12.3 M NaOH solution
Solution 2 = 1.2 M NaOH solution
<span>
Solving for volume 1, volume 1 = (12.4 L * 1.2 M)/12.3 M = 0.1366 L </span>
A sodium atom forms NA+1 ion by losing two electrons
