A2.50-g sample of powdered zinc is added to 100.0 ml of a 2.00-m aqueous solution of hydrobromic acid in a calorimeter. the total heat capacity of the calorimeter and solution is 448 j/k. the observed increase in temperature is 21.1 k at a constant pressure of one bar. using these data, calculate the standard enthalpy of reaction. zn(s) + 2hbr(aq) --> znbr2(aq) + h2(g)

247 kJ/mol

Explanation:

Zn(s) + 2HBr(aq) → ZnBr₂(aq) + H₂(g)

First, we need to find the limiting reactant.  And to do that, we need to find the amount of moles of each reactant.

2.50 g Zn * (1 mol / 65.38 g) = 0.03824 mol Zn

0.1000 L * 2.00 mol/L = 0.200 mol HBr

Since 1 mol of Zn reacts with 2 mol of HBr, it is clear that Zn is the limiting reactant.

The amount of heat can be calculated as:

q = (448 J/K) * (21.1 K)

q = 9452.8 J

So the standard enthalpy of reaction is:

ΔH = (9452.8 J) / (0.03824 mol Zn)

ΔH = 247 kJ/mol

that tool is called an altimeter which measures your altitude which can be used to tell which atmosphere you are currently in, including the stratosphere.

hope this ! : )

what experimental evidence led scientists to change from the previous model to this one?

a few of the positive particles aimed at a gold foil seemed to bounce back.

the colors of light emitted from heated atoms had very specific energies.

experiments with water vapor showed that elements combine in specific proportions.

cathode rays were bent in the same way whenever a magnet was brought near them.