1. Untitled by Li Shangyin:
"In spring, silkworms will weave until they die, and the wax torch will turn to ash and let it dry."
There are both melting process in physical change and burning phenomenon in chemical change. The composition of candle is paraffin wax, which belongs to saturated hydrocarbon. Exothermic combustion in air can melt solid paraffin into liquid wax droplets.
2. Wang Anshi's January Day:
"The explosion happened a year ago, and the spring breeze sent it to Tu Su."
This is a typical chemical change. Firecrackers are generally made of sulfur and other substances, which react chemically after being ignited to generate new substances such as sulfur dioxide.
3. Liu Kun's Gift for Lu Chen:
"Why do you want to make all kinds of steel and turn it into a winding element?" In fact, "steelmaking" is a process of continuously removing impurities from pig iron to make it pure.
4. Li Bai's Song of Autumn Pu:
"The fire shines on heaven and earth, and the red star is purple."
This poem also describes the scene of metal smelting at that time.
5. Yu Qian's Ode to Lime in Ming Dynasty:
"One thousand hammer dug out, fire shut.
Don't be afraid of being smashed to pieces, leaving innocence in the world. "
It is not easy to mine limestone, which refers to physical changes. In this poem, "burning" refers to the chemical reaction of calcining limestone to produce calcium oxide and carbon dioxide. Coupled with the words "if leisure", people feel that this is not only burning limestone, but also symbolizes that people with lofty ideals are taking their time and treating it as leisure no matter how severe the test is. "Broken into pieces" embodies the changes of the body and expresses the spirit of not being afraid of sacrifice. Keeping the world innocent is the author's straightforward expression and his determination to be a pure and innocent person.
Yu Qian's other object-chanting poem "Ode to Coal": "Digging chaos will bring black gold, and the most profound sun will be saved. Fire will revive spring, and the red furnace will break the night. Ding yiyuan is generated by strength, and the stone remains after death. I hope that the whole life is full of warmth and I will go out of the mountains tirelessly. " The author focuses on the formation, characteristics, properties and main uses of coal in the whole poem, and with the help of
The above is for reference.
2.( 1) is expressed in chemical terms: two iron atoms (1)① represent multiple atoms, and corresponding numbers are added before their element symbols, so two iron atoms can be expressed as 2Fe；; (2) In its chemical formula, elements are represented by symbols and numbers, with symbols in front and numbers behind; For example, the oxide of tetravalent sulfur element can be expressed as+4SO2; (2)① Representation method of ions: If multiple ions are represented, the corresponding numbers are added before the element symbols, so the meaning of 3Al 3+ is: 3 aluminum ions; 2 c+o 2 ignition. The meanings of CO 2 are: (optional) substance reaction: carbon reacts with oxygen to produce carbon dioxide; Microscopic significance: a carbon atom reacts with an oxygen molecule to generate a carbon dioxide molecule; Macro significance: 12 parts of carbon can react with 32 parts of oxygen to generate 44 parts of carbon dioxide, so the answer is: (1)12fe; ②+4S O2； (2)①3 aluminum ions; ② Carbon reacts with oxygen to produce carbon dioxide.
3. What are the basic knowledge and classic questions about the quantity of chemical substances in Grade One? The following description of the quantity of substances is urgent. The error is that A. 1 mol any substance contains 6.02* 1023 molecules; B.0.0 12 kg 12C contains about 6.02* 1023 CC. 1 mol water contains 2 mol of hydrogen and 1 mol of oxygen D. 1024 e- Analysis because some substances are composed of molecules. ), some substances are composed of ions (such as NaCl, Ca(OH)2, etc. ), and some substances are directly composed of atoms (such as diamonds, etc.). ), the description of a is wrong. Carbon is made up of atoms. According to the regulations, the number of carbon atoms contained in 0.0 12 kg 12C is Avon Gadereau constant, and its approximate value is 6.02* 1023 mol- 1, so B's statement is correct. According to the regulation, "when the amount of substance is expressed in moles, the chemical formula should be used to indicate the type of particles, not the Chinese name of particles". The meanings of hydrogen and oxygen are not specific, so they are not correct. There are 10 electrons outside the neon nucleus, so 1 mol Ne should also contain 10 * 6.02 * 1023 electrons, so the statement of D is correct. Answer AC shows that when learning chemical concepts, you must read the words related to the concepts carefully. When using the quantity and unit of substance, the type of particle must be expressed by chemical formula, and the Chinese name cannot be used to prevent the meaning from being unclear. Example 2 How many water molecules does 0.2 mol H2O contain? How many hydrogen atoms are there in these waters? Avon Garderot constant was used to analyze 1 mol H2O containing multiple H2O molecules; There are two H's and 1 O's in the molecule 1 H2O. According to n=, then n (H2O) = n.na Using this formula, the number of H2O molecules contained in 0.2 mol H2O can be calculated. N (H2O) = n (H2O) * Na = 0.2 mol * 6.02 * 1023 mol-1=1.204 *1023 n (h) = 2n. 1023=2.408* 1023 or n (h) = 2n (H2O) = 2 * 0.2mol = 0.4mol n (h) = n (h) na = 0.4mol * 6.02 *1023mol. 1023 The answer is that the number of H2O molecules in 0.2 mol H2O is 1.204* 1023, in which the number of hydrogen atoms is 2.408* 1023. It shows that 1 H2O contains 2 H and 1 O, and 1 mol H2O contains 2h and 1 mol o. It is more practical to describe microscopic particles by the amount of substances. Example 3 How many grams of water can 4g NaOH dissolve to dissolve one Na+ per 100 H2O molecule? Analysis 1 mol NaOH was dissolved in water, and 1 mol Na+ and 1 mol OH- were ionized. Every 100 H2O molecule dissolves one Na+, that is, =, n(Na+)=n(NaOH)=, therefore, m (H2O) is found. N (Na+) = n (NaOH) = = 0. 1mol. According to the meaning of the question, N (H2O) =100n (Na+) =100 * 0.1mol = 65438+ 18g mol-1= 180g Answer: Dissolve 4 g NaOH in180g water, and one Na+ can be dissolved in every 100 water molecules. It shows that the quantity of matter is an important bridge between quality and particle number, so we should learn and master this communication method flexibly.