After evaporation of m g of water from the solution having a mass fraction of a solute, it becomes V ml of a sodium hydroxide unsaturated solution having a mass fraction of 2 a of solute What is the concentration of the substance obtained?

After evaporation of m g of water from the solution having a mass fraction of a solute, it becomes V ml of a sodium hydroxide unsaturated solution having a mass fraction of 2 a of solute What is the concentration of the substance obtained?

Suppose you have xg of solution
The NaOH mass before and after evaporation remain unchanged
X*a%==(x-m)*2a%
X ==2 m
Then NaOH has 2m*a%/40=0.0005ma mol
The concentration is 0.0005ma/(V/1000)==0.5ma/Vmol/L

What are the common lattice types of metals? What is the difference in their crystal structure

Lattice types of common metals
There is a strong binding force between metal atoms, so the atoms in metal crystals tend to be closely aligned. However, different metals have different crystal structures, and the crystal structures of most metals are relatively simple, among which the following three are common:
(1) Body-centered cubic lattice (bcc)
The unit cell of the body-centered cubic lattice is a cube, as shown in Fig.2-2-4. Its lattice constant: a=b=c,α=β=γ=90. There is one atom at each of the eight corners of the cube and the center of the cube. The actual number of atoms in each unit cell is 1+8×1/8=2. The nearest neighbor of each atom is 8, so its coordination number is 8. The density is 0.68. The metals with the body-centered cubic lattice are chromium (Cr), tungsten (w), molybdenum (Mo), vanadium (V),α-iron (α-Fe), etc.
(2) Fcc
The unit cell of the face-centered cubic lattice is also a cube, and the metal atoms are distributed on the eight corners and the center of the six faces of the cubic lattice, as shown in Fig.2-2-5. Its lattice constant: a=b=c, the actual number of atoms contained in each unit cell is (1/8)×8+6×(1/2)=4, the coordination number is 12, and the density is 0.74. The metals with the face-centered cubic lattice are aluminum (Al), copper (Cu), nickel (Ni), gold (Au), silver (Ag),γ iron (γ-Fe), etc.
3) Hexagonal (hcp)
The unit cell of the closely arranged hexagonal lattice is a regular hexagonal cylinder, which is composed of six rectangular side surfaces and two regular hexagonal bottom surfaces, as shown in Fig.2-26. The metal atoms are distributed on the twelve corners of the hexagonal cell and in the three uniformly distributed gaps between the center of the upper and lower bottom surfaces and the two bottom surfaces. The unit cell is represented by two lattice constants, one is the side length a of the hexagon, and the other is the height c of the cylinder. The actual number of atoms contained in each unit cell is (1/6)×12+2×(1/2)+3=6. The typical closely arranged hexagonal lattice constant c and a is about 1.633, The metal with dense hexagonal lattice is Mg, Zn, Cd, etc.
Variance:
The above three lattices have different atomic arrangement, so their properties are also different. Generally speaking, BCC materials have higher strength and lower plasticity; FCC materials have lower strength and better plasticity; and dense hexagonal materials have lower strength and plasticity.