There are 4 things that are evidence of a chemical change.
1)Change in color
2)Change in shape (gas being let out)
3)Change in temperature
4)Change in smell
Burning wood is a chemical change because it has a change in color, and shape.
Answer:
5010J
Explanation:
The following data were obtained from the question:
Mass (m) = 15g
Heat of fusion (ΔHf) = 334J/g
Heat required (Q) =..?
The heat energy required to melt the ice can be obtained as follow:
Q = m·ΔHf
Q = 15 x 334
Q = 5010J
Therefore, the heat energy required to melt the ice is 5010J.
Answer:
3.07 × 10⁻⁴
Explanation:
Step 1: Calculate the concentration of H⁺
We will use the definition of pH.
![pH = -log [H^{+} ]\\\[ [H^{+} ] = antilog -pH = antilog -2.37 = 4.27 \times 10^{-3} M](https://tex.z-dn.net/?f=pH%20%3D%20-log%20%5BH%5E%7B%2B%7D%20%5D%5C%5C%5C%5B%20%5BH%5E%7B%2B%7D%20%5D%20%3D%20antilog%20-pH%20%3D%20antilog%20-2.37%20%3D%204.27%20%5Ctimes%2010%5E%7B-3%7D%20M)
Step 2: Calculate the concentration of HY
5.22 × 10⁻³ mol of HY are dissolved in 0.088 L. The concentration of the acid (Ca) is:
Step 3: Calculate the acid dissociation constant (Ka)
We will use the following expression.
![Ka = \frac{[H^{+}]^{2} }{Ca} = \frac{(4.27 \times 10^{-3} )^{2} }{0.0593} = 3.07 \times 10^{-4}](https://tex.z-dn.net/?f=Ka%20%3D%20%5Cfrac%7B%5BH%5E%7B%2B%7D%5D%5E%7B2%7D%20%7D%7BCa%7D%20%3D%20%5Cfrac%7B%284.27%20%5Ctimes%2010%5E%7B-3%7D%20%29%5E%7B2%7D%20%7D%7B0.0593%7D%20%3D%203.07%20%5Ctimes%2010%5E%7B-4%7D)
