Answer:
heat capacity: "the number of heat units needed to raise the temperature of a body by one degree."
Explanation:
There are 618.68 g in 4.5 moles of NaF.
The total number of moles of any substance equals the ratio of its given mass in a chemical reaction to the mass of one mole or molar mass of that substance.
It is known that one mole of NaF or molar mass of NaF is 41.98 g/mol.
Given that number of moles is 4.5 moles.
Therefore, calculate the mass of NaF in grams as follows.
No. of moles = Given mass / Molar mass
mass in grams = No. of moles × Molar mass
= 4.5moles × 41.98 g/mol
= 188.91 g
Hence, we can conclude that there are 188.91 g in 4.5 moles of NaF.
Learn more about NaF from the link given below.
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Answer:
Grease is insoluble in water but soluble in kerosene
Explanation:
The molecules in grease are non polar molecules and so can not react with water which is polar to generate enough solvation energy. On the other hand kerosine is non polar so reacts with grease to generate enough solvation energy to dissolve it.
Explanation:
require an emergency support immediately
Answer:In alpha decay, shown in Fig. 3-3, the nucleus emits a 4He nucleus, an alpha particle. Alpha decay occurs most often in massive nuclei that have too large a proton to neutron ratio. An alpha particle, with its two protons and two neutrons, is a very stable configuration of particles. Alpha radiation reduces the ratio of protons to neutrons in the parent nucleus, bringing it to a more stable configuration. Many nuclei more massive than lead decay by this method.
Consider the example of 210Po decaying by the emission of an alpha particle. The reaction can be written 210Po Æ 206Pb + 4He. This polonium nucleus has 84 protons and 126 neutrons. The ratio of protons to neutrons is Z/N = 84/126, or 0.667. A 206Pb nucleus has 82 protons and 124 neutrons, which gives a ratio of 82/124, or 0.661. This small change in the Z/N ratio is enough to put the nucleus into a more stable state, and as shown in Fig. 3-4, brings the "daughter" nucleus (decay product) into the region of stable nuclei in the Chart of the Nuclides.
In alpha decay, the atomic number changes, so the original (or parent) atoms and the decay-product (or daughter) atoms are different elements and therefore have different chemical properties.
Upper end of the Chart of the Nuclides
In the alpha decay of a nucleus, the change in binding energy appears as the kinetic energy of the alpha particle and the daughter nucleus. Because this energy must be shared between these two particles, and because the alpha particle and daughter nucleus must have equal and opposite momenta, the emitted alpha particle and recoiling nucleus will each have a well-defined energy after the decay. Because of its smaller mass, most of the kinetic energy goes to the alpha particle.