The number is written in scientific notation.
The significant figures are the numbers known precisely plus 1 digit that is uncertain.
When the numbers are expressed in scientific notation all the digits before 10^n are significant.
So, 7 and 8 are significant figures and the answer is that the number of significant figures is 2.
Answer: 2
The answer is 10 grams.
The atomic weights for each elements are :
<span>Na - 22.99 g/mol </span>
<span>O - 16.00 g/mol </span>
<span>H - 1.01 g/mol
The sum = 40 g/mol for NAOH
</span><span>0.250 moles * 40.00 g / 1 mole = 10 g NaOH</span>
Moles Li = 3.50 g / 6.941 g/mol= 0.504
the ratio between Li and N2 is 6 : 1
moles N2 required = 0.504 /6=0.0840
we have 3.50 g / 28.0134 g/mol=0.125 moles of N2 so N2 is in excess
the ratio between Li and Li3N is 6 : 2
moles Li3N = 0.504 x 2 /6=0.168
mass Li3N = 0.168 mol x 34.8297 g/mol=5.85 g
Answer:
0.019 g.
Explanation:
- Firstly, we need to find the no. of moles of oxygen gas:
- We can use the general law of ideal gas: <em>PV = nRT.
</em>
where, P is the pressure of the gas in atm (P = 1.02 atm).
V is the volume of the gas in L (V = 15.0 L).
n is the no. of moles of the gas in mol (n = ??? mol).
R is the general gas constant (R = 0.0821 L.atm/mol.K),
T is the temperature of the gas in K (T = 28°C + 273 = 301.0 K).
∴ n = PV/RT = (1.02 atm)(15.0 L)/(0.0821 L.atm/mol.K)(301.0 K) = 0.62 mol.
- To find the mass of oxygen gas, we have:
<em>no. of moles = mass/molar mass.</em>
<em></em>
∴ mass of oxygen = (no. of moles)(molar mass) = (0.62 mol)(32.0 g/mol) = 0.019 g.
