The rate of a reaction refers to the speed at which the reaction takes place. The rate of a reaction depends on many variables such as, temperature, concentration of dissolved reactants, pressure of gaseous reactants, surface area of solid reactants, or the presence of a catalyst. In order to measure the rate of a reaction, we must measure the change in amount of a reactant as it is consumed over time, or measure the amount of product formed over time. When you graph the formation of a product, or consumption of a reactant on the y axis, versus the time of reaction on the x-axis, the slope of this function will provide the rate of the reaction.
Answer:
18.4 g
Explanation:
M(He) = 4.0 g/mol
4.6 mol * 4.0 g/ 1 mol = 18.4 g
<span>Mass percentage is one way of representing the concentration of an element in a compound or a component in a mixture. </span>To calculate percent by mass, you need to determine two things: the mass of just the element, and the molar mass of the whole compound. We calculate as follows:
.10 g NaCl / g NaCl + Water = ( 10.0 g NaCl + x ) / (10.0 g + 255 g + x )
x = 18.33 g NaCl needed