The sun burns 600 million tons of hydrogen into helium every second, and lasts 10 billion years...?

Question

The sun burns 600 million tons of hydrogen into helium every second, and lasts 10 billion years. Can someone help me compute what percentage of its total mass is lost? Why does the rest of the hydrogen in the sun also burn, letting the sun have a much longer life?

Answer 1

The percent lost per second?
That would be
600 million / 10 billion = 0.06

Answer 2

The energy [or "E"] given off by the fusion process of 400 or 600 or 700 depending upon your source million tons of mass [or "m"] is found by the famous ratio equation E=mc^2. Some of the mass is turned into helium and some at a rate of c^2 gets turned into photons or quanta of electromagnetic radiation aka energy.
I cannot fully follow your last question. The Sun will undergo hydrogen fusion until all the hydrogen is used up. The hydrogen being there allows it to get used. Then, it will stop, eject some mass into space, shrink a tiny bit to achieve temperatures and pressures great enough to begin to go helium fusion which will cause it to swell and become a red giant. After all the helium is used up, it will eject some more mass off and eventually end up as a white dwarf.

Answer 3

You know how much is converted every second. Now all you have to do is find out how many seconds are in 10 billion years, multiply that by the amount converted every second. Then compare that with the total mass of the Sun.

For hydrogen to fuse into helium, the hydrogen has to be at very high temperatures and pressures - the type of temperature and pressure that's only found at the core of the Sun, and not anywhere outside of the core - the core is the hottest and densest place.

Answer 4

I found a source that says "In units of tons, every second, the Sun's fusion processes are converting about 700 million tons of hydrogen into helium "ashes". In doing so, 0.7 percent of the hydrogen matter (5 million tons) disappears as pure energy."

In other words, very little of of that 600 million (or 700 million) tons is lost mass. 99.3% of the hydrogen mass is converted to helium mass. Only 0.7% is lost to energy a la E=mc^2.

The site goes on to compute the percentage of mass that is expected to be lost in the remaining lifespan of the sun. (It is much easier to do this in kilograms):

"... we find that the Sun loses mass 4.289x10^12 g every second to energy. Or, in other units, the Sun loses mass 1.353x10^20 g every year to energy."

And since the sun is expected to live for 5 billion more years (5x10^9) ...

"Mass = (1.353x10^20 g/year) * 5x10^9 years = 6.8 x 10^29 g

Since the Sun's current mass is 1.989 x 10^33 g, the percentage of its current mass that will be converted to energy is:

6.8 x 10^29 g / 1.989 x 10^33 g = 0.00034 of its current mass or .034 percent.

In other words, the Sun's mass at the end of its lifetime is 99.966% of its current mass."

As for your second question ... I don't understand. As long as there is hydrogen, it will continue to burn. Why should it stop? (Unless you were theorizing that so much mass was lost that the gravitational pressure would cease, and the fusion would stop. ... But now, as you can see, not that much mass is lost.)