Answer:
Ca:
Explanation:
A Lewis structure shows the number of valence electrons about an atom.
Ca is in Group 2 of Period 4.
Its electron configuration is [Ar]4s².
Thus, Ca has two valence electrons and its Lewis structure is Ca:
Answer:
0.642 g
Explanation:
La ecuación balanceada es:
- 2Mg + 2CuSO₄ + H₂O → 2MgSO₄ + Cu₂O + H₂
Primero <u>convertimos 1.89 g de Cu₂O en moles</u>, usando su <em>masa molar</em>:
- 1.89 g ÷ 143.09 g/mol = 0.0132 mol Cu₂O
Después <u>convertimos moles de Cu₂O en moles de Mg</u>, usando los <em>coeficientes estequiométricos</em>:
- 0.0132 mol Cu₂O * = 0.0264 mol Mg
Finalmente <u>convertimos moles de Mg en gramos</u>, usando la <em>masa molar de Mg</em>:
- 0.0264 mol Mg * 24.305 g/mol = 0.642 g
Flexible connections are used because bridges sway. If there were steel or non flexible connections, the road would crumble. Another reason is steel would expand or contract in the heat or cold. If the steel expanded or contracted, then the road would be weak. And since the people on the road don't want it to crumble, the architect put flexible connections instead of hard ones.
4 moles of sodium because you originally have 2.0 moles of Na2SO4 and you set that up at the beginning of the (what we called) train tracks. Then diagonally from that, on the bottom you put 1 mol of Na2SO4 to cancel the units. Then above that you have 2 moles of sodium because that is how many there are in the equation that they gave (the Na2 part). Then its just like a fraction, you multiply the top by the top and the bottom by the bottom, which would give you 4moles/1 or just 4 moles Na. I hope that helps