Answer:
Explanation:
Better digestion!!
A teacher asks students to describe the physical properties of 10 mL of vinegar and 10 mL of milk. When the students finish listing the physical properties in their science notebooks, the teacher pours the vinegar and milk into the same beaker. The students are surprised to see a white solid substance form within the beaker as the two substances are combined.
What occurs within the beaker as the teacher mixes the vinegar and milk?
1. A chemical change that produces a precipitate
2. A physical change that creates a new substance
3. A physical change that produces a precipitate
4. A chemical change that produces no new substances
Answer:
1. A chemical change that produces a precipitate
Explanation:
A solid substance that is formed from a liquid phase is called a precipitate.
A reaction that produces a precipitate is called a precipitation reaction.
Precipitation reactions are an example of a chemical change.
Thus the correct answer is option 1: A precipitate was formed when vinegar and milk were mixed (as there were no solid substances when they were apart).
If 240.0 g NaOH reacts, how many grams of Cu(OH)2 should precipitate out in the reaction? Show work
Answer:
292.7 g
Explanation:
Note: the reaction is missing but I looked it up on the web and found it.
Step 1: Write the balanced equation
CuSO₄(aq) + 2 NaOH(aq) → Cu(OH)₂(s) + Na₂SO₄(aq)
Step 2: Calculate the moles corresponding to 240.0 g of NaOH
The molar mass of NaOH is 40.00 g/mol.
240.0 g × 1 mol/40.00 g = 6.000 mol
Step 3: Calculate the moles of Cu(OH)₂ formed from 6.000 moles of NaOH
The molar ratio of NaOH to Cu(OH)₂ is 2:1. The moles of Cu(OH)₂ formed are 1/2 × 6.000 mol = 3.000 mol.
Step 4: Calculate the mass corresponding to 3.000 moles of Cu(OH)₂
The molar mass of Cu(OH)₂ is 97.56 g/mol.
3.000 mol × 97.56 g/mol = 292.7 g
1. What kinds of metals are REALLY reactive? why?
2. What kinds of non-metals are REALLY reactive? why?
3. What group on the periodic table doesn’t react at all? why?
Answer:
1. Alkali metals (group 1)
2. halogens (Group 17)
3. noble gasses (group 18)
Explanation:
1. alkali metals only have one valence electron meaning that they really want to lose that one valence electron to get a full octet.
2. halogens have 7 valence electrons meaning that they just need to gain 1 to get a full octet.
3. Nobel gasses already have a full octet meaning that they don't want to react. (atoms only react to get a full octet)
I hope this helps. Let me know if anything is unclear.
The enthalpy of combustion of gasoline (C8H18) is 5471 kJ mol-1. How much heat will be produced by burning 1 gallon of gasoline at 25°C? (Density of gasoline = 0.703 g/mL; 1gallon = 3.78 L) Show your work clearly.
Answer:
127529 KJ
Explanation:
Since 1gallon = 3.78 L= 3780 ml
The density of C8H18= 0.703 g/mL
Density = mass/volume
Mass= Density × volume
Mass= 0.703 g/mL × 3780 ml
Mass= 2657.34 g
Molar mass of C8H18= 114 g/mol
Number of moles= mass/molar mass
Number of moles= 2657.34/114
Number of moles= 23.31 moles
Since 1 mole evolved=5471 kJ
23.31 moles = 5471 kJ × 23.31 = 127529 KJ