energy is required to move from one state or phase of matter to the next. Energy is used to make a liquid into a gas or a solid into a liquid.
4. A
because PbCl2 is an ionic compound and it's solid, so it's a substance.
It cannot be mixture, because it's a pure molecule.
5. D
despite that both substances are gases, colorless they are different molecules, so they should have different either chemical and physical properties
6. C
this substance made from W atoms and others are made from molecules
Answer:
0.17 moles
Explanation:
In the elements of the periodic table, the atomic mass = molar mass. <u>Ex:</u> Atomic mass of Carbon is 12.01 amu which means molar mass of Carbon is also 12.01g/mol.
In order to find the # of moles in a 12 g sample of NiC-12, we will need to multiply the number of each atom by its molar mass and then add the masses of both Nickel and C-12 found in the periodic table:
- Molar Mass of Ni (Nickel): 58.69 g/mol
- Molar Mass of C (Carbon): 12.01 g/mol
Since there's just one atom of both Carbon and Nickel, we just add up the masses to find the molar mass of the whole compound of NiC-12.
- 58.69 g/mol of Nickel + 12.01 g/mol of Carbon = 70.7 g/mol of NiC-12
There's 12g of NiC-12, which is less than the molar mass of NiC-12, so the number of moles should be less than 1. In order to find the # of moles in NiC-12, we need to do some dimensional analysis:
- 12g NiC-12 (1 mol of NiC-12/70.7g NiC-12) = 0.17 mol of NiC-12
- The grams cancel, leaving us with moles of NiC-12, so the answer is 0.17 moles of NiC-12 in a 12 g sample.
<em>P.S. C-12 or C12 just means that the Carbon atom has an atomic mass of 12amu and a molar mass of 12g/mol, or just regular carbon.</em>
Equation for the standard formation of solid sodium orthosilicate:
4 Na(s) + Si(s) + 2 O₂(g) → Na₄SiO₄(s)
<span>To solve this exercise you need to know that to create CO₂ with C₂H₂ is necessary to have oxygen. So, the following balanced equation represents the reaction:
2C₂H₂(g) + 5O₂(g) → 4CO₂(g) + 2H₂O(g)
Notice that 2 moles of C₂H₂ form 4 moles of </span><span>CO₂, so if </span>3.3 moles of C₂H₂ react, how many moles of CO2 would be produced?
2 moles <span>of C₂H₂ -------</span>4 moles of <span>CO₂
3.3 </span><span>moles <span>of C₂H₂--------x moles of CO₂
x=6.6 </span></span><span>moles of CO₂ produced.</span>
