Due to their improved charge transfer and great environmental stability, 2D Dion-Jacobson (DJ) perovskites have recently received a lot of attention.
Unfortunately, due to the scarcity of high-quality single crystals for precise measurements, their fundamental optoelectronic capabilities are mainly unknown. Here, a reactive, low-temperature-gradient crystallization method is created using 1,4-butanediammonium as a short-chain insulating spacer to generate high-quality 2D perovskite single crystal (BDAPbI4). It is discovered that the BDAPbI4 single crystal exhibits a direct bandgap with effective charge collection (μτ = 1.45 × 10−3 cm2 V−1). The BDAPbI4 single crystal in particular exhibits the expected high ion migration activation energy (0.88 eV).
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It's 2) a positively-charged nucleus is surrounded by mostly empty space (aka Rutherford's Model).
Most of the atom's mass is inside the nucleus (which contains protons [+] and neutrons [0 charge]), while the electrons [-] "float" around the nucleus like clouds. This is why it's said that the atom is 'mostly empty space'.
a. We first calculate the moles of sucrose needed
moles sucrose = 0.250 M * 0.25 L
moles sucrose = 0.0625 mol
The molar mass of sucrose 342.3 g/mol, so the mass of
sucrose needed is:
mass sucrose = 0.0625 mol * 342.3 g/mol
mass sucrose = 21.4 grams
So simply dissolved about 21.4 grams of sucrose in 250 mL
solution.
b. We use the formula:
M1 V1 = M2 V2
1.50 M * V1 = 0.100 M * 0.350 L
V1 = 0.0233 L = 23.3 mL
So simply take 23.3 mL of solution from 1.50 M then dilute
it with water until 350 mL to make 0.100 M.
Answer: The density of 0.50 grams of gaseous carbon stored under 1.50 atm of pressure at a temperature of -20.0 °C is 0.867 g/L.
Explanation:
- d = m/V, where d is the density, m is the mass and V is the volume.
- We have the mass m = 0.50 g, so we must get the volume V.
- To get the volume of a gas, we apply the general gas law PV = nRT
P is the pressure in atm (P = 1.5 atm)
V is the volume in L (V = ??? L)
n is the number of moles in mole, n = m/Atomic mass, n = 0.50/12.0 = 0.416 mole.
R is the general gas constant (R = 0.082 L.atm/mol.K).
T is the temperature in K (T(K) = T(°C) + 273 = -20.0 + 273 = 253 K).
- Then, V = nRT/P = (0.416 mol)(0.082 L.atm/mol.K)(253 K) / (1.5 atm) = 0.576 L.
- Now, we can obtain the density; d = m/V = (0.50 g) / (0.576 L) = 0.867 g/L.
