Answer:
1.60.
Explanation:
- The no. of millimoles of HCl = MV = (0.15 M)(20.0 mL) = 3.0 mmol.
- The no. of millimoles of KOH = MV = (0.10 M)(20.0 mL) = 2.0 mmol.
<em>Since the no. of millimoles of HCl is larger than that of KOH. The solution is acidic.</em>
<em></em>
∴ M of remaining HCl [H⁺] remaining = (NV)HCl - (NV)KOH/V total = (3.0 mmol) - (2.0 mmol) / (40.0 mL) = 0.025 M.
∵ pH = - log[H⁺]
<em>∴ pH = - log[H⁺] </em>= - log(0.025) = <em>1.602 ≅ 1.60.</em>
Answer:
The change in energy when a neutral atom in the gaseous state adds an electron to form a negative ion.
Explanation:
That is, it is the energy involved in the reaction
X(g) + e⁻ ⟶ X⁻(g)
For most elements, the electron affinity is negative.
However, there are two major exceptions — the values are positive for the elements of Groups 2 and 18 (note the troughs in the graph below).
N - 15 undergoes beta decay and has a half-life of less than 1 minute.
Answer:
78.2 g/mol
Step-by-step explanation:
We can use the <em>Ideal Gas Law</em> to solve this problem:
pV = nRT
Since n = m/M, the equation becomes
pV = (m/M)RT Multiply each side by M
pVM = mRT Divide each side by pV
M = (mRT)/(pV)
Data:
ρ = 2.50 g/L
R = 0.082 16 L·atm·K⁻¹mol⁻¹
T =98 °C
p = 740 mmHg
Calculation:
(a)<em> Convert temperature to kelvins
</em>
T = (98 + 273.15) = 371.15 K
(b) <em>Convert pressure to atmospheres
</em>
p = 740 × 1/760 =0.9737 atm
(c) <em>Calculate the molar mass
</em>
Assume V = 1 L.
Then m = 2.50 g
M = (2.50 × 0.082 06 × 371.15)/(0.9737 × 1)
= 76.14/0.9737
= 78.2 g/mol
