Answer: A) grinding coffee beans
Explanation:
A physical change is defined as a change in which there is alteration in shape, size etc. No new substance gets formed in these reactions.
A chemical change is defined as a change in which a change in chemical composition takes place. A new substance is formed in these reactions.
1. Grinding coffee : Only change in size takes place, thus a physical change
2. Baking a cake: the chemical reaction occurs by combination of flour with oxygen , thus a chemical change.
3.:converting water to hydrogen and oxygen: The decomposition iof water takes place, thus is a chemical change
4.Burning of coal: the chemical reaction occurs by combination of carbon with oxygen , thus a chemical change.
Answer:
Al + 4AgNO3 >>Al(NO3)3+ 3Ag
Explanation:
the number of moles of No3 of the products is 3 therefore we have to balance the reactants by adding 3 before the "AgNO3" which also leades us to adding 3 mols to Ag on the products side
Answer:
1.03 atm
Explanation:
Primero <u>convertimos 21 °C y 37 °C a K</u>:
- 21 °C + 273.16 = 294.16 K
- 37 °C + 273.16 = 310.16 K
Una vez tenemos las temperaturas absolutas, podemos resolver este problema usando la<em> ley de Gay-Lussac</em>:
En este caso:
Colocando los datos:
- 294.16 K * P₂ = 310.16 K * 0.98 atm
Y <u>despejando P₂</u>:
Answer:
matter cannot be created nor destroyed
Explanation:
Answer:
2.6 mole of lithium bromide have 225.81 g.
Explanation:
Given data:
Number of moles of lithium bromide = 2.6 mol
Mass of lithium bromide = ?
Solution:
Formula:
<em>Number of moles = mass/ molar mass</em>
Molar mass of lithium bromide = 86.85 g/mol
Mass = number of moles × molar mass
Mass = 2.6 mol ×86.85 g/mol
Mass = 225.81 g
Thus 2.6 mole of lithium bromide have 225.81 g.
