Answers:
See below
Step-by-step explanation:
1. Most food energy
(a) Pringles
Heat from Pringles + heat absorbed by water = 0
m₁ΔH + m₂CΔT = 0
1.984ΔH + 100 × 4.184 × 18 = 0
1.984ΔH + 7530 = 0
ΔH = -7530/1.984 = -3800 J/g
(b) Cheetos
0.884ΔH + 418.4 × 13 = 0
ΔH = -5400/0.884 = -6200 J/g
Cheetos give you more food energy per gram.
(c) Snickers
Food energy = 215 Cal/28 g × 4184 J/1 Cal = 32 000 J/g
The food energy from Cheetos is much less than that from a Snickers bar
2. Experimental uncertainty
The experimental values are almost certainly too low.
Your burning food is heating up the air around it, so much of the heat of combustion is lost to the atmosphere.
3. Percent efficiency
Experimental food energy = 3800 J/g
Actual food energy = 150 Cal/28 g × 4184 J/1 Cal = 22 000 J/g
% Efficiency = Experimental value/Actual value × 100 %
= 3800/22 000 × 100 %
= 17 %
Answer:
7.01 g
Explanation:
Answer:- Mass of the titanium alloy is 7.01 g, choice C is correct.
Solution:- The heat of fusion is given as 422.5 joules per gram and it also says that 2960 joules of heat is required to melt the metal completely.
The suggested equation is, Q=mHf
where Q is the heat energy, m is the mass and Hf is the heat of fusion.
Since, we are asked to calculate the mass, the equation could be written as:
m=q/H5
Let's plug in the values in it:
m= 2960J/ 422.5j/g
m = 7.01 g
So, the mass of the titanium alloy is 7.01 g, choice C is correct.
Answer:
Because of the tilt of Earth on its axis, Earth's surface and atmosphere are unevenly heated by the Sun. Convection currents form in the atmosphere as warmer air rises and cooler air sinks.
Mendeleev's periodic table
Dmitri Mendeleev
Like many scientists working at the end of the 19th-century the Russian chemist Dmitri Mendeleev (1834-1907) was looking for ways to organise the known elements. Mendeleev published his first periodic table of the elements in 1869.
Features of Mendeleev's tables
Mendeleev arranged the elements in order of increasing relative atomic mass. When he did this he noted that the chemical properties of the elements and their compounds showed a periodic trend. He then arranged the elements by putting those with similar properties below each other into groups. To make his classification work Mendeleev made a few changes to his order:
he left gaps for yet to be discovered elements
he switched the order of a few elements to keep the groups consistent
Be 1s²2s², [He]2s²
beryllium (2- second period, s² - 2A group)
