Answer:
Number of Na ions in 14.5 g of NaCl is 1.49 × 10²³.
Number of Cl ions in 14.5 g of NaCl is 1.49 × 10²³.
Total number of ions = 1.49 × 10²³ + 1.49 × 10²³ = 2.98 × 10²³.
Explanation:
1 mole of any compound contains 6.023 × 10²³ molecules.
molecular weight of NaCl is 23 + 35.5 = 58.5 g.
so, 58.5 grams of NaCl makes 1 mole
⇒ 14.5 g of NaCl = = 0.248 moles.
⇒ 0.248 mole contains 0.248 × 6.023×10²³ molecules
= 1.49 × 10²³ molecules.
And 1 molecule contains 1 Na ion and 1 Cl ion.
⇒ number of Na ions in 14.5 g of NaCl is 1.49 × 10²³.
⇒ number of Cl ions in 14.5 g of NaCl is 1.49 × 10²³.
Total number of ions = 1.49 × 10²³ + 1.49 × 10²³ = 2.98 × 10²³.
The correct answer is letter C
From the balanced equation, we can see that 1 mole of CH4
releases 802.3 kJ of heat upon combustion. The mass of 1 mole of CH4 is:
mass CH4 = 16.04 grams
So by ratio and proportion:
mass required = (-268 kJ) / (-802.3 kJ / 16.04 grams)
<span>mass required = 0.334 grams</span>
A. carbon
b. the carbon atoms in diamond have a lot of strong covalent bonds with other carbon atoms. which are conjoined in a 3d structure. This means the ‘giant covalent structure’ of diamonds is very difficult to break, making diamonds very hard.
However, the carbon atoms in graphite have less covalent bonds, and graphite is structured in sheets of atoms with weak forces holding them together - this means these sheets can slide off easily and come apart from the structure. Therefore, graphite is very soft.