Greetings Everyone,

So I am a new DM running my first campaign. One of my players is playing the Artificer class, subclass Alchemist. 

As I understand it, this type of casting is based upon the use of some sort of alchemist supplies in order to produce the desired spell effects. In Newtonian physics for every action, there is an equal opposite reaction. So looking at the Artificer spell list some spells do not have spell components (Ex. Cure wounds), so:

A) Does this mean that the Artificer (Alchemist) is not creating an alchemical reaction to produce the spell?

B) If the Artificer (Alchemist) IS creating an Alchemical reaction would the character be consuming supplies in order to produce the effect?

My concern is that the player will lose all spellcasting ability because they used up all of their supplies before they even reached the objective. They have been traveling to a temple but it has been over multiple days since they have been to the town. Additionally, this class/subclass has a feat (Alchemical Savant) in regards to alchemical spells, I do not want unfairly nullify this feat because of my Newtonian Physics hang up. If anyone can provide some assistance that would be really great. 

Well, spellcatsers can heal without a 'reaction' so let's take a deep breath and think this through.

An artificer/alchemist appears to draw his abilities through manipulations of the Natural world, so in a way they must be some sort of super scientist of their day.  But we need to consider what the game does for us to keep the players balanced.  Is the Alchemist's ability to heal breaking the game?  Is he Crazy more powerful than the other players as a result?  Probably not.  So I would think the reason they don't mention it is because he can find the components rather easily while he is traveling.  Therefore, since he doesn't need to buy components or spend hours and hours finding them, maybe the game just sort of 'hand-waves' that away.

If things are fairly balanced among your players and everyone is having fun then let the Rule of Cool … Rule.  Go with it and spend more time thinking about encounters and the story.

If things aren't balanced then look at what you can do to dial it in.  Talk to the player offline and together develop a solution.  Good luck & have fun.

Well this isn't really Newtonian Physics. This is Magical Chemistry. The thing your player is paying is spell slots, which are essentially magic energy focused through their alchemist supplies. They get this energy from resting, eating, and generally living. Were they using a component pouch, it may be slightly similar, but the components would be a focus of sorts, and in most cases they are not consumed. I think you're digging too far into the RP. RAW doesn't have their alchemist supplies used upon cast, and so I wouldn't either. That said, there are limits to what Artificers can do, and when they exceed those limits, material consumption would probably come into play.

You may be overthinking this. The best help I can offer is to not apply Newtonian Physics to how magic works in D&D. Magic is not a completely understood force in the D&D universes. That is why Gods such Azuth and Mystra favor those who study the weave and spell casting because not even gods of magic know everything about magic. Lots of different things can cause the same effects need to cast spells. Using your example of cure wounds which is a verbal and somatic spell. In order to cast these spells one needs to speak some sort of spoken incantation and do some sort of gesture. It’s vague, intentionally. Artificers flavor there spells as using “science” and ”engineering” to create some sort of reaction in the weave to cast their spells. Your PC maybe an Alchemist subclass but all Artificers are engineers too. That’s why they have proficiency in Tinker tools, it’s fundamental to their class. To cast their spells they could for example, create a simple device like a steampunk or clockwork rubric cube that has a small metal hand spring out and  causes the same verbal and somatic effects needed cast cure wounds. And this device could change into different configurations to cast other spells. Preparing the device in certain configurations to cast different spells . The alchemist can it flavor is as maybe adding maybe a special reagent or compound they created to act as the medium to cast the spell. This medium could be consumed if the spell consumes the spell components. But otherwise I wouldn’t limit your players spell to their alchemical supplies, same with alchemical savant. Also I would advise against limiting or nullifying a player’s class feature unless this was something you discussed in a session zero. Otherwise, you risk isolating that player and affecting their enjoyment of the game. They probably chose this class for a reason. But getting back to the other thing have the alchemical reagent act as a spellcasting focus or medium could be how you player flavors casting their spells. I hope this was helpful. 

tl/dr: no the artificer does not produce an alchemical reaction in order to cast their spells. They flavor it however the want

Googagon this was very helpful. I felt that my thinking (the reason why I posted on the forum) was going down a rabbit hole and very unfairly against my player. 

The artificer text clarifies some of the flavor through the choice of spellcasting focus:

Tools Required

You produce your artificer spell effects through your tools. You must have a spellcasting focus—specifically thieves’ tools or some kind of artisan’s tool—in hand when you cast any spell with this Spellcasting feature. You must be proficient with the tool to use it in this way.

THE MAGIC OF ARTIFICE

As an artificer, you use tools when you cast your spells. When describing your spellcasting, think about how you’re using a tool to perform the spell effect. If you cast cure wounds using alchemist’s supplies, you could be quickly producing a salve. If you cast it using tinker’s tools, you might have a miniature mechanical spider that binds wounds. When you cast poison spray, you could fling foul chemicals or use a wand that spits venom. The effect of the spell is the same as for a spellcaster of any other class, but your method of spellcasting is special.

The same principle applies when you prepare your spells. As an artificer, you don’t study a spellbook or pray to prepare your spells. Instead, you work with your tools and create the specialized items you’ll use to produce your effects. If you replace cure wounds with heat metal, you might be altering the device you use to heal—perhaps modifying a tool so that it channels heat instead of healing energy.

Such details don’t limit you in any way or provide you with any benefit beyond the spell’s effects. You don’t have to justify how you’re using tools to cast a spell. But describing your spellcasting creatively is a fun way to distinguish yourself from other spellcasters.

Mechanically, since the player can use alchemists supplies/tinker's tools/some other tools as a focus, that means the presence of those tools counts as all of the material components of the spell that don't have a listed cost. So the player doesn't have to track just how many eyes of newt they have with them or whatever.

Something to remember is that the rules of D&D are very abstract. A fun way to flavor things may be to think of spell slots as representing whatever base alchemical components they need to do their stuff, rather than as some innate magical stamina. When they finish their long rest, they regain spell slots by mixing up new bases. Casting specific spells through their tool focus could be thought of as adding whatever you need to evoke the particular reaction you want for the specific spell you're casting to the pre-mixed foundation and letting it fly.

Spellcasting foci aren't consumable resources, which can be interpreted in a bunch of different ways. For example, maybe the amount it requires is just negligible, and you're not in any realistic danger of running out before you can restock (off-camera, such things don't need to be explicitly dealt with, it's an abstract game). Or, perhaps as part of the pre-mixing in the morning, the alchemist distills out whatever they added the day before and puts it back in their alchemist's tools focus. The rules are like quantum physics: they only prescribe the math. How you interpret what it means in reality is very flexible.

Just like a wizard with a component pouch, an alchemist using alchemical reagents as a "spellcasting focus" shouldn't need to worry about running out of equipment to fuel their spell slots.  It's just understood that, in off-time during rests or between adventures, the character is likely topping off their component stores. 

If you enjoy having a scientific approach to alchemy, you can consider that alchemists consider all things to be comprised of the same handful of elements and that alchemy is about breaking things down and recombining them based proportions of these elements. So an artificer doesn't need to go to town to get ingredients. In fact, small towns likely wouldn't carry them because only artificers can make them. What they need is time and tools and matter to manipulate. During a long rest alchemists can break down rocks and sticks into solvents and salves because that's what makes them alchemists - cause anyone can apply a salve.

"Alchemy, the science of understanding the structure of matter, breaking it down, then reconstructing it as something else. It can even make gold from lead. But alchemy is a science so it must follow the natural laws: to create, something of equal value must be lost. This is the principal of equivalent exchange. But I learned that night that some things cannot be measured on a simple scale. My brother and I knew the laws of science, of equivalent exchange. The game required sacrifice, that something had to be taken from us, but we thought there was nothing more we could loose....We were wrong."
 - Edward Elric(Fullmetal Alchemist)